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TM 11-6625-493-15

DEPARTMENT OF THE ARMY TECHNICAL MANUAL

DS, GS, AND DEPOT MAINTENANCE

MANUAL

FREQUENCY COMPARATOR

CM-77A/USM

This copy is a reprint which includes current pages from Changes 1 through 4.

HEADQUARTERS, DEPARTMENT OF THE ARMY

SEPTEMBER 1964

Page 2

Page 3

Changes in force C1, C3, and C4

Operators, Organizational, Direct Support,

General Support, and Depot

Maintenance Manual

FREQUENCY COMPARATOR CM977A/USM

(NSN 6625-00-080-7204)

TM 11-6625-493-15, 29 September 1964, is changed as follows:

The title of the manual is changed as shown above. Page v, The Forms and Records paragraph is

superseded as follows:

TM 11-6625-493-15

HEADQUARTERS

DEPARTMENT OF THE ARMY

ASHINGTON , DC, 9 May 1977

0-1. Forms and Records

a. Reports of Maintenance and Unsatisfactory

Equipment. Maintenance forms, records, and reports

which are to be used by maintenance personnel at all maintenance levels are listed in and prescribed by TM 38-750.

b. Report of Packaging and Handling Deficien-

cies. Fill out and forward DD Form 6 (Packaging Im-

provement Report) as prescribed in AR 70058/NAVSUPINST 4030.29/AFR 71-13/MCO P4030.29A, and DSAR 4145.8.

c. Discrepancy in Shipment Report (DISREP) (SF

361). Fill out and forward Discrepancy in Shipment Report (DISREP) (SF 361) as prescribed in AR 5538/NAVSUPINST 4610.33A/AFR

4610.19B and DSAR 4500.15 The Reporting of Errors paragraph is superseded as follows:

75-18/MCO

0-2. Reporting of Errors

You can help improve this manual by calling atten tion to errors and by recommending improve-

ments and stating your reasons for the recommendations. Your letter or DA Form 2028 (Recommended Changes to Publications and Blank Forms) should be mailed direct to Commander, US Army Electronics

Command, ATTN: DRSEL-MA-Q, Fort Monmouth, New Jersey 07703. A reply will be furnished direct to you. After the Reporting of Errors paragraph, add the following:

0-3. Administrative Storage

Administrative storage of equipment issued to and used by Army activities shall be in accordance with

TM 740-90-1.

0-4. Destruction of Army Electronics

Materiel.

Destruction of Army electronics materiel to prevent

enemy use shall be in accordance with TM

750-244-2.

0-5. Reporting Equipment improve-

ment Recommendations (EIR)

EIR’s will be prepared using DA Form 2407 (Maintenance Request). Instructions for preparing EIR’s are provided in TM 38-750, The Army Maintenance Management System. EIR’s should be mailed direct to Commander, US Army Electronics Command, ATTN: DRSEL-MA-Q, Fort Monmouth, New Jersey

07703. A reply will be furnished direct to you. Page 5-2, Table 5-1 is superseded as follows:

Page 4

Table 5-1. Test Equipment

Page 5.1-1. Section V.I is superseded as follows:

SECTION V.1

PREVENTIVE MAINTENANCE INSTRUCTIONS

5.1-1. Scope of Organizational Preventive Maintenance

Preventive maintenance is the systematic care, servicing, and inspection of equipment to prevent the occurrence of trouble, to reduce downtime, and to assure that the equipment is serviceable.

a. Systematic Care. The procedures given in tables 5.1-1 and 5.1-2 cover routine systematic care essential to proper upkeep and operation of the equipment.

b. Preventive Maintenance Checks and Services. The preventive maintenance checks and services tables outline the functions to be performed at specific intervals. These checks and services are designed to maintain Army equipment in a combatserviceable condition; that is, in good physical and operational condition. To assist organizational

maintenance personnel in maintaining combat serviceability, the table indicate what to check, how to

check, and the normal conditions. If the defect cannot be remedied by organizational maintenance personnel, higher category maintenance or repair is required. Records and reports of these checks and services must be made in accordance with TM 38-750.

5.1-2. Preventive Maintenance Checks and Services Periods

Preventive maintenance checks and services of the equipment is required on a daily, weekly, and monthly basis as indicated in a and b below. Whenever a normal indication is not observed during the performance of the daily, weekly, or monthly preventive maintenance check, necessary corrective action must be taken.

a. Daily and Weekly. Table 5.1-1 specifies the preventive maintenance checks and services that must be performed daily and weekly or when the

equipment is:

(1) Initially installed.

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(2) Reinstalled after return from higher cate

gory of maintenance and repairs have been performed.

(3) Maintained in a standby (ready for immedi-

ate operation) condition. Perform on a monthly schedule.

ly 30 calendar days of 8-hour-per-day operation. Ad-

justment of the monthly preventive maintenance in-

terval must be made to compensate for any unusual

operating conditions. For example, if the equipment

is used 16 hours per day, the monthly preventive

(4) Returned to service from limited storage. maintenance checks and services should be per-

b. Monthly. Table 5.1-2 specifies the preventive

maintenance checks and services that must be per-

formed monthly. A month is defined as approximatc-

formed at 15-day intervals. ACM-77A maintained in

a standby condition requires monthly preventive

maintenance, but one in limited storage does not.

Table 5.1-1. Daily and Weekly Preventive Maintenance Checks and Services

para 3-6

Table 5.1-2. Monthly Preventative Maintenance Checks and Services

para 5-4 and 5-5

5.1-3. Cleaning

Inspect the exterior of the equipment. The exterior should be clean, and free from dust, dirt, grease, and fungus.

a. Remove dust and loose dirt with a clean lint-

free cloth.

WARNING

The fumes of trichloroethane are toxic. Provide thorough ventilation whenever used.

paragraph 5-3

DO NOT USE NEAR AN OPEN FLAME. Trichloroethane is not flammable, but exposure of the fumes to an open flame or hot metal forms highly toxic phosgene gas.

b. Remove grease, fungus, and ground-in dirt from the case; use a cloth dampened (not wet) with trichloroethane. After cleaning, wipe dry with a clean lint-free cloth.

c. Remove dust or dirt from plugs and jacks with

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a soft-bristled brush.

CAUTION

Do not press on the face (glass) of the cathode ray tube when cleaning; the cathode ray tube may become damaged.

d. Clean the front panel and control knobs; use a soft clean lint-free cloth. If necessary, dampen the cloth with water. Mild soap may be used for more effective cleaning. cloth .

Wipe dry with a clean lint-free

5.1-4. Paints and Finishes

When the CM-77A/USM requires repainting, refinishing, or touchup painting, refer to Federal Standard No. 595a for a matching color. SB 11-573

lists. painting tools and miscellaneous supplies required for painting.

5.1-5. Touchup Painting Instructions

a. Refer to TB 43-0118 for instructions on paint-

ing and preserving Electronics Command equip-

ment. When touchup painting, a perfect match with the exact shade of the original paint surface may not be possible. This may be caused by changes such as in the original pigment because of oxidation, and differences in manufacture. The prevention of corrosion and deterioration is the most important consideration in touchup painting; appearance is secondary.

This, however, should not be construed to mean that

appearance of the equipment is not important.

Touckup painting should be accomplished neatly

and the quality of work should be good. Field inspection personnel should make allowances for slight color mismatch where minor touchup has been done, but not for neglect, poor quality, or where the need for refinishing is obvious.

b. Remove rust and corrosion from metal surfaces

by lightly sanding them with fine sandpaper. Brush

two thin coats of paint on the bare metal to protect it from further corrosion.

Page i-2. Appendix 1 is superseded as follows:

APPENDIX A

REFERENCES

The following is a list of references that are available to the operator and organizational, DS, GS, and depot maintenance personnel of Frequency Comparator CM-77A/USM:

DA Pam 310-4

DA Pam 310-7 SB 11-573

TB 43-180 TB 43-0118

TM 11-6625-200-15

TM 11-6625-258-14

TM 11-6625-274-12

TM 11-6625-316-12

TM 11-6625-320-12

TM 11-6625-366-15

TM 11-6625-412-15-1

Index of Technical Manuals, Technical Bulletins, Supply Manuals (Types 7, 8 and

9), Supply Bulletins, and Lubrication Orders. US Army Index of Modification Work Orders. Painting and Preservation Supplies Available for Field Use for Electronics

Command Equipment. Calibration Requirements for the Maintenance of Army Materiel. Field Instructions for Painting and Preserving Electronics Command Equipment

Including Camouflage Pattern Painting of Electrical Equipment Shelters Operator’s, Organizational,

Multimeters ME-26A/U, ME-26B/U, ME-26C/U, and ME-26D/U. Operator’s, Organizational, Direct Support, and General Support Maintenance

Manual: Signal Generators SG-299/U, SG-299A/U, SG-299B/U, SG-299C/U,

SC-299D/U and SG-299E/U. Operator’s and Organizational Maintenance Manual: Test Sets, Electron Tube

TV-7/U, TV-7A/U, TV-7B/U, and TV-7D/U.

Operator’s and Organizational Maintenance Manual: Test Sets, Electron Tube

TV-2/U, TV-2A/U, TV-2B/U, and TV-2C/U.

Operator’s and Organizational Maintenance Manual: Voltmeter, Meter

ME-30A/U and Voltmeters, Electronic ME-30B/U, ME-30C/U, and ME-30E/U. Operator’s, Organizational, EM, CS, and Depot Maintenance Manual: Multimeter

TS-352B/U.

Operator, Organizational, DS, GS, and Depot Maintenance Manual,

Repair Parts and Special Tools List: Radio Test Set AN/URM-44A.

DS, GS, and Depot Maintenance Manual:

Including

Page 7

TM 11-6625-700-14-1

TM 11-6625-1703-15

TM 38-750 TM 740-90-1 TM 750-244-2 Procedures for Destruction of Electronics Materiel to Prevent Enemy Use

Page i-3, Appendix II is superseded as follows:

Operator’s, Organizational, Direct Support, and General Support Maintenance

Manual Including Repair Parts and Special Tools List (Including Depot Maintenance Repair Parts and Special Tools): Digital Readout Electronic Counter AN/USM-207A (Serial Nos. 1A through 1100A).

Operator, Organizational, DS, GS, and Depot Maintenance Manual Including

Repair Parts and Special Tool Lists: Oscilloscope AN/USM-281A.

The Army Maintenance Management System (TAMMS).

Administrative Storage of Equipment

(Electronics Command).

APPENDIX C

MAINTENANCE ALLOCATION

Section I. INTRODUCTION

C-1. General

This appendix provides a summary of the

maintenance operations for CM-77A/USM. It authorizes categories of maintenance for specific maintenance functions on repairable items and components and the tools and equipment required to perform each function. This appendix may be used as an aid in planning maintenance operations.

C-2. Maintenance Function

Maintenance functions will be limited to and defined as follows:

a. Inspect. To determine the serviceability of an item by comparing its physical, mechanical, and/or electrical characteristics with established standards through examination.

b. Test. To verify serviceability and to detect incipient failure by measuring the mechanical or electrical characteristics of an item and comparing those

characteristics with prescribed standards.

c. Service. operations required periodically to

keep an item in proper operating condition, i.e., to clean (decontaminate), to preserve, to drain, to paint,

or to replenish fuel, lubricants, hydraulic fluids, or

compressed air supplies.

d. Adjust. To maintain, within prescribed limits,

by bringing into proper or exact position, or by setting the operating characteristics to the specified parameters.

e. Align. To adjust specified variable elements of

an item to bring about optimum or desired performance.

f. Calibrate. To determine and cause corrections to be made or to be adjusted on instruments or test measuring and diagnostic equipments used in precision measurement. Consists of comparisons of two instruments, one or which is a certified standard of known accuracy, to detect and adjust any discrepancy in the accuracy of the instrument being compared.

g. Install. The act of emplacing, seating, or fixing into position an item, part, module (component or assembly) in a manner to allow the proper functioning of the equipment or system.

h. Replace. The act of substituting a serviceable like type part, subassembly, or module (component or assembly) for an unserviceable counterpart.

i. Repair. The application of maintenance serv-

ices (inspect, test, service, adjust, align, calibrate, re-

place) or other maintenance actions (welding, grind-

ing, riveting, straightening, facing, remachining, or

resurfacing) to restore serviceability to an item by correcting specific damage, fault, malfunction, or failure in a part, subassembly, module (component or assembly), end item, or system. This function does not include the trial and error replacement of run-

ning spare type items such as fuses, lamps, or elec-

tron tubes.

j. Overhaul. That maintenance effort (service/ action) necessary to restore an item to a completely serviceable/operational condition as prescribed by maintenance standards (i.e., DMWR) in appropriate technical publications. Overhaul is normally the highest degree of maintenance performed by the

Page 8

Army. Overhaul does not normally return an item to like new condition.

k. Rebuild. Consists of those services/actions necessary for the restoration of unserviceable equipment to a like new condition in accordance with

original manufacturing standards. Rebuild is the highest degree of materiel maintenance applied to Army equipment. The rebuild, operation includes the act of returning to zero those age measurements (hours, miles, etc.) considered in classifying Army equipments/components.

C-3. Column Entries

a. Column 1, Group Number. Column 1 lists group numbers, the purpose of which is to identify components, assemblies, subassemblies, and modules with the next higher assembly.

b. Column 2, Component/Assembly. Column 2 contains the noun names of components, assemblies, subassemblies, and modules for which maintenance is authorized.

c. Column 3, Maintenance Functions. Column 3 lists the functions to be performed on the item listed in column 2. When items are listed without maintenance functions, it is solely for purpose of having the group numbers in the MAC and RPSTL coincide.

d. Column 4, Maintenance Category. Column 4 specifies, by the listing of a “work time” figure in the appropriate subcolumn(s), the lowest level of maintenance authorized to perform the function listed in column 3. This figure represents the active time required to perform that maintenance function at the indicated category of maintenance. If the number or complexity of the tasks within the listed maintenance function vary at different maintenance categories, appropriate “work time” figures will be shown for each category. The number of task-hours specified by the “work time” figure represents the average time

required to restore an item (assembly, subassembly, component, module, end item or system) to a service-

able condition under typical field operating conditions. This time includes preparation time, troubleshooting time, and quality assurance/quality control time in addition to the time required to perform the

specific tasks identified for the maintenance func-

tions authorized in the maintenance allocation cha Subcolumns of column 4 are as follows:

C - Operator/Crew O - Organizational F - Direct Support H - General Support D - Depot

e. Column 5, Tools and Equipment. Column specifies by code, those common tool sets (not in dividual tools) and special tools, test, and supper equipment required to perform the designated func tion.

f. Column 6, Remarks. Column 6 contains an al

phabetic code which leads to the remark in section

IV, Remarks, which is pertinent to the item opposite

the particular code.

C-4. Tool and Test Equipment

Requirements (Sect. Ill)

a. Tool or Test Equipment Reference Code. The

numbers in this column coincide with the numbers

used in the tools and equipment column of the MAC. The numbers indicate the applicable tool or test equipment for the maintenance functions.

b. Maintenance Category. The codes in this column indicate the maintenance category allocated the tool or test equipment.

c. Nomenclature. This column lists the noun name and nomenclature of the tools and test equipment required to perform the maintenance functions.

d. National/NATO Stock Number. This column lists the National/NATO stock number of the specific

tool or test equipment.

e. Tool Number. This column lists the manufacturer’s part number of the tool followed by the

Federal Supply Code for manufacturers (5-digit) in

parentheses.

C-5. Remarks (Sect. IV)

a. Reference Code. This code refers to the appropriate item in section II, column 6.

b. Remarks. This column provides the required

explanatory information necessary to clarify items

appearing in section II.

Page 9

TM 11-6625-493-15

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Figure 1-1

Model 540B

Figure 1-1. Model 540B, Front View

Page 23

TM 11-6625-493-15

FOREWORD

Throughout this manual, reference is made to Model 540B Transfer

oscillator which is a commercial designation and is identical with Frequency comparator CM-77A/USM. This is a first-edition manual containing preliminary and unreviewed information compiled by the manufacturer of the equipment. Judicious caution should be exercised in using the information in this manual until it is replaced by a revised edition.

Index of Equipment Publications

Refer to the latest issue of DA Pam 31C-4 to determine whether there are new editions, changes, or additional publications pertaining to the equipment. Department of the Army Pamphlet No. 310-4 is an index of current technical manuals, technical bulletins, supply manuals, supply bulletins, lubrication orders, and modification work orders available through publications supply channels. The index lists the individual parts (-10, -20, -35P, etc) and the latest changes to and revisions of each equipment publication.

Forms and Records

Reports of Maintenance and Unsatisfactory Equipment. Use equipment forms and records in accordance with instructions in TM 38-750.

Report of Damaged or Improper Shipment. Fill out and forward DDForm 6

(Report of Damaged or Improper Shipment) as prescribed in AR 700-58 (Army),

NAVSANDA Publication 378 (Navy), and AFR 71-4 (Air Force).

Reporting of Equipment Manual Improvements. The direct reporting, by the individual user, of errors, omissions, and recommendations for

improving this equipment manual is authorized and encouraged. DA Form 2028 till be used for reporting these improvements. This form may be completed by using pencil, pen, or typewriter. triplicate and forwarded by the individual using the manual.

DA Form 2028 will be completed in

The original and one copy will be forwarded direct to: Commanding General, U. S. Army Electronics Command, ATTN: AMSEL-MR-(NMP)-MA,

Fort Monnouth, New Jersey

07703.

Page 24

Page 25

Model 540B Section I

Paragraphs 1-1 to 1-10

SECTION I

GENERAL INFORMATION

1-1. INTRODUCTION.

1-2.

PURPOSE AND USE. The Hewlett - Packard Model 540B Transfer Oscillator is an electronic frequency-measuring instrument which, extends the frequency measurement range of the Hewlett - Packard

524 and 5243 series of electronic frequency counters into the microwave region. The transfer oscillator frequency counter combination measure frequencies up to 12.4 gigacycles (gc), or with an external mixer, up to 18 gc, with near-counter accuracy. The Model

540B can also be used without a frequency counter to measure frequency below 4 gc within about ± 1/2%.

1-3. The method used in the Model 540B Transfer Oscillator to determine frequency is to zero-beat the unknown input signal with a harmonic of an extremelystable signal generated in the 540B, and to measure the 540B fundamental frequency on a counter. Multi-

plying the counter readout by the number of the har-

monic causing the zero-beat gives the input signal frequency. The harmonic number is determined either

from previous knowledge of the input frequency or by

computation. The zero-beat is displayed on the 540B internal oscilloscope. Typical difference-frequency displays obtained are shown in figures 3-4 and 3-5.

1-4.

The visual dieplay of the difference frequency between two signals permits reading microwave carrier frequencies to very close tolerance while the signal is being amplitude- or frequency-modulated, or when it contains troublesome e amounts of noise. It also permits measuring the incidental frequency modulation in amplitude-modulated carriers, the residual frequency modulation in cw signals and the center frequency and Iimits of deviation in frequency-modulated signals. When the 540B is used in conjunction with an external oscilloscope, the carrier frequency of rf

pulses can also be measured to high accuracy. Typical

beat-frequency displays of pulse-modulated carriers are shown in figures 3-10 and 3-11.

1-5. ACCURACY OF MEASUREMENT. The stability of the transfer oscillator and the precision with which it can be adjusted are sufficient that the high accuracy and resolution of the electronic counters used for readout are utilized over the entire frequency range. Accuracies up to 1 part per million may be expected with cw signals that are very stable and noise-free. Few radio-frequency (rf) signals are stable enough to be measured with such accuracy. Thus, the instability of the signal being measured is usually the greatest accuracy-limiting factor.

1-6. When measuring pulsed signals, accuracy de-

pends to some extent on pulse length because measurement can take place only during the pulse. Typical accuracy obtainable when measuring a stable, pulsed

carrier of 1000 mc is approximately 3 parts per million for a 10-microsecond pulse duration and 10 parts

per million for a 2. 5-microsecond pulse.

1-7. DESCRIPTION OF EQUIPMENT. The trans-

fer oscillator is a single-unit, cabinet-mounted in-

strument.

The electronic circuitry haa four main groups which can be interconnected by front panel jumpers for a variety of measurement applications.

The four groups are shown in the block diagram in

figure 1-2, and listed below:

a. Oscillator Section. An internal oscillator generates a frequency from 100 to 220 mc, which is continuously adjustable by front panel controls. This

frequency is applied to frequency mixers and to an

external frequency counter for accurate frequency indication.

b. Frequency Mixers. There are two mixers, a low frequency mixer for input signals from about 10 mc to 5 gc and a high frequency mixer for input sig-

nals from 1 gc to 12.4 gc. The oscillator output is

connected to the proper mixer through a front panel

jumper. The mixer generates harmonics of the oscil-

lator signal which beat with the input signal and pro-

duce low-frequency beat signals which constitute the

mixer output.

c. Amplifier-Oscilloscope Section The amplifier amplifies the mixer output to display the beat frequency on the built-in oscilloscope. The amplified mixer output is also available for display on an external oscilloscope.

With the mixer output being displayed on the oscilloscope, the frequency of the oscillator can be adjusted until one of its harmonica produces a zero-beat indication. The zero-beat indi-

cation on the oscilloscope differs in shape as different types of signals having varying amounts of modulation or noise are measured.

d. Harmonic Generator. This separate harmonic generator section may be used to produce higherorder harmonics of the oscillator frequency for external amplification and use.

1-8.

ACCESSORIES FURNISHED. The Model 540B Transfer Oscillator includes as part of the equipment a 6-inch coaxial cable jumper with type BNC connectors for use in programming connections between the

jacks on the front panel, and a 4-foot coaxial cable

with type BNC connectors for connecting the transfer oscillator to the electronic counter.

1-9. DIFFERENCES IN INSTRUMENTS.

1-10. This manual applies directly to 540B Transfer Oscillators having the serial-number prefix 234. The manual with the following changes aleo applies to 540B Transfer Oscillators having serial-prefix numbers

128, 046, 015, 008, and the earlier prefix 129 for serials between 101 and 597.

00161-2

1-1

Page 26

Section I

Table 1-1

Model 540B

Table 1-1. Specifications

GENERAL

Frequency Range: 10 mc to at least 12.4 gc Type of Input Signal: CW, AM, FM, or pulse

Maximum Input: 100 mw

Accuracy: Depends on character of unknown sig-

nal, accuracy of comparison, and accuracy with which fundamental is measured. See discussion

in text.

Auxiliary Equipment:

Model 524 Sertes Electronic Counter Model 525B Frequency Converter Unit

Model 150A Oscilloscope (for pulse measure-

m ent)

OSCILLATOR Fundamental Frequency Range: 100 mc to 220 mc

OSCILLOSCOPE

Frequency Range: 100 cps to 200 kc Vertical Deflection Sensitivity: 5 mv rms per inch Horizontal Sweep:

External, 1 volt per inch, 20 cps to 5 kc

Internal, power supply frequency with phase

control

MISCELLANEOUS Dimensions:

Cabinet Mount: 20-3/4 in. wide, 12-1/2 in. high,

15-1/4 in. deep

Harmonic Frequency Range: Above 12.4 gc Stability: Less than 0.002% change per minute after

30 minutes warmup

Dial: Six-inch diameter, calibrated in l-me in-

crements. Accuracy ± 1/2%

Vernier Dial:

Mechanical - approximately 9:1 Electrical -

approximately ± 125 parts/million

Output: Approximately 2 volts into 50 ohms. Ad-

justed for optimum crystal harmonic generation.

AMPLIFIER Gain: Adjustable, 40 db maximum

Bandwidth: 100 cycles to 2 megacycles High Frequency Control: 3-db point adjustable from

below 1 kc to above 2 mc

Low Frequency Control: 3-db point switched from

100 cycles to below 10 kc, then continuously adjustable to above 400 kc

Maximum Undistorted Output: 1 volt rms usable

signal across 1000-obm load

1-2

Weight: Cabinet Mount: 42 lb, shipping 53 lb

Rack Mount:

35 lb, shipping 50 lb

Power Supply: 115 or 230 volts ± 10%, 50 to 1000

cps, approximately 110 watts

bly, 3 ft of RG-58/U 50-ohm coaxial cable termi-

nated at each end with UG-88/U type BNC male connectors

Accessories Available:

50-ohm coaxial cable terminated at one end with

a UG-21B/U type male connector and with a UG-

23 B/U type N female connector at the other. (For

use at frequencies below 4000- mc. )

50-ohm coaxial cable terminated at one end only

with a UG-88/U type N BNC male connector

ohm coaxial cable terminated at each end with

UG-21B/U type N male. connectors.

(For use

at frequencies; below 4000 mc. )

treated RG-9A/U 50-ohm coaxial cable terminated at each end with UG-21B/U type N male connectors.

Each cable is tested and selected

for minimum vswr at frequencies above 4000 mc.

00161-2

Page 27

Model 540B

Section I

Paragraph 1-11

Figure 1-2. Diagram of Panel Connections and Functional Groups

1-11. To adapt this manual to instruments with other instrument serials, make changes as follows:

Instrument Serial No.

129-01577 to 128-02701 046-01191 to 046-01516 015-00698 to 015-01190 008-598 to 008-697 129-00101 to 128-00597

Change No.

1, 2 1, 2 1, 2, 3 1, 2, 3 1, 3, 4

1. S4. Delete slide switch from schematic diagram, parts lists, table 3-1. Refer to paragraph 2-9 for details.

Q1, R76, R77, C49. Delete these parts from sche-

matic diagram, parts lists, and replace with R2,

Resistor, fixed, composition, 1200 ohms ± 10%,

2. Gear, frequency drive, large driving; change stock number in parts lists to G36-H.

Gear, frequency drive, large spring loading; change

stock number in parts lists to G24-G.

Window, frequency dial; change stock number in parts lists to G99-H.

L8. Delete choke from schematic diagram and parts Mats. Replace with wire jumper connected to junction of J13 and L5.

Regulated B+ at Vll pins 3 and 6; change to +225 volts, Decrease by about 7% the values of all tube socket voltages listed for all tubes except V6, V8,

V10, Vll, V12, and V13.

R12. Change value to 27,000 ohms, 0690-2731.

R17. Change value to 1800 ohms,

0687-1821. C47. Change value to 470 pf,

0027,

Gear, frequency drive, large driving; change

stock No. in parts lists to 200AB-36B. Gear, frequency drive, large spring loading; change

stock No. in parts lists to 200AB-36C.

00161-1

1-3/1-4

Page 28

Page 29

Model 540B

Paragraphs 2-1 to 2-13

Section II

SECTION II

INSTALLATION

2-1. UNPACKING AND INSPECTION

2-2.

Unpack the Transfer Oscillator upon receipt and inspect it for signs of physical damage such as scratched or dented surfaces, bent or broken projections, etc.

operation of the instrument as a further check for damage in shipment. Preserve the packing materials

and case for future reshipment. The materials are designed to give best protection against normal shipping hazards.

2-3. REPACKING FOR SHIPMENT.

2-4. If possible use original packing materials and

carton for repacking. If it is not available, first wrap

instrument in plastic of smooth, heavy paper to pro-

tect surface against scratching. Use liberal quantity

“stuffing” between entire instrument and heavy

shipping carton or box. The stuffing materials should

be firm, should prevent motion of the instrument in

the container, and absorb vibration as much as pos-

sible. Seal the shipping carton with steel bands or

heavy tape.

"DELICATE INSTRUMENT”.

2-5. POWER CABLE.

2-6. The Transfer Oscillator is equipped with a three-conductor power cable which, when plugged into the appropriate receptacle, grounds the instrument

chassis. The offset round pin on the plug is the ground

connection. To preserve the ground connection when

using a three-pin to two-pin adapter in a two-pin re-

ceptacle, connect the green pigtail lead on the adapter to ground (the receptacle mounting box may provide

a good ground connection).

Mark the shipping box “FRAGILE” -

When possible, also attempt

and install the jumper marked “230 v“. The connections are easily made on a tie strip mounted next to the power transformer.

Figure 2-1. Power Transformer Primary Winding

2-10. OPERATION ON LINE FREQUENCIES

HIGHER THAN 120 CYCLES PER SECOND

2-11. The Transfer Oscillator can be operated on any

frequency from 50 to 1000 cycles per second. The in-

ternal sweep for the front-panel oscilloscope gives

adequate phase control with line frequencies up to 120

cps. Above this line frequency, the proper degree of phase control can still be obtained by decreasing the value of C24 according to the following equation:

For example: with 400 cps line frequency,

2-7. OPERATION FROM 115- OR 230-VOLT LINE.

2-8. The Transfer Oscillator may be operated on either 115- or 230-volt line as selected by a slide switch on the rear of the instrument chassis (earlier models were not equipped with this switch and required rewiring of the power transformer primary winding as described below). The slide switch can be operated with a screwdriver; for operation on 115 volts, slide switch down so that “115” is exposed; use a 1.25amp fuse. For 230-volt operation, slide switch down so that “230” is exposed; use a O. 75-amp fuse.

2-9. For Transfer Oscillators having serial number prefixes 129, 048, 015, and 008, the power transformer primary winding was connected as shown in figure 2-1 for 115-volt operation. To connect for 230volt operation remove the jumpers marked “115 v“

00161-2

2-12. lNSTALLATION

2-13. No special operating precautions are necessary

for installing the Transfer Oscillator except when it is

to be operated near vibrating machinery. Even though

the precision oscillator in the Model 540B is not prone

to microphonics, its extreme resolution makes very

small frequency changes readily observable, and the

effects of vibration may become apparent. If vibrating machines disturb frequency measurements, shockmount the Transfer Oscillator by placing the cabinet

model on shock-absorbing material

mounted, the mass of the rack is often sufficient to reduce vibration to tolerable amounts. rack-mounting the Transfer Oscillator are given in Table 1-1, Specifications.

When rack-

Details of

2-1

Page 30

Section III

Figure 3-1

Model 540B

3-0

Figure 3-1. Measuring CW and FM Signals

Page 31

Model 540B

Paragraphs 3-1 to 3-5

Section III

SECTION Ill

OPERATING INSTRUCTIONS

3-1. INTRODUCTlON. 3-2. This section gives step-by-step procedures for

measuring the frequency of the three most common types of microwave signals, continuous wave, frequency modulated and pulsed signals. The instructions for measuring c-w signals are basic to all measurements made with the Transfer oscillator and must be understood before proceeding with any other measurement technique.

special uses of the Transfer oscillator.

Apply no more than 100 milliwatt r-f power to the Transfer oscillator Input connectors. To do so will damage the mixer crystal diodes.

3-3. MEASURING FREQUENCY.

3-4. GENERAL. To measure the frequency of an unknown signal applied to the input of the Transfer

Oscillator, tune the 540B fundamental frequency until a harmonic of this fundamental beate with the input

signal, then measure the fundamental frequency on an

electronic counter (or read it from the FREQUENCY dial) and multiply the fundamental by the number of the harmonic which beat with the input signal; the product

is the frequency of the input signal. When measuring an input signal for the first time, one of two conditions exists: 1) the frequency of the input signal is known approximately and the number of the harmonic causing the beat can be determined by dividing the approximate

input signal frequency by the fundamental and rounding

off the answer to the nearest whole number; 2) the input

signal frequency is completely unknown and the number

of the harmonic that beats with it must be determined by tuning the 540B to two adjacent fundamental frequen-

cies whose harmonics zero beat with the input signal,

and computing the number of the harmonic, and the

input frequency.

3-5. To measure the frequency of an input signal refer to figures 3-1, 3-3 and Table 3-1, and proceed as follows:

a. Plug in power cable and turn power switch to the

ON position.

b. Select the mixer section which includes the frequency of the signal to be measured. Connect the jumper cable between the OSCILLATOR OUTPUT and OSCILLATOR INPUT connectors of this mixer.

Instructions are aleo included for

CAUTION

e. Determine if the input signal level is above 100 milliwatts. If it ie, provide attenuation as shown in figure 3-1.

CAUTION

DO NOT EXCEED 100 milliwatts to either SIGNAL INPUT connector. will destroy the crystal diodes in the mixer. The minimum signal input power required to make measurements at various frequencies is shown in figure 3-2.

The values obtainable with a particular mixer may vary from the average values shown due to different crystal efficiencies, etc. Generally variations as great as ± 10 db from tbe curves may occur at some frequencies. *DBM means decibels referred to one milliwatt.

Figure 3-2. Typical Mixer Input Sensitivity

f. Connect the input signal to be measured to the

SIGNAL INPUT connector of the selected mixer.

g. Connect the electronic counter (Hewlett-Packard Model 524 C/D or equivalent) to the FREQUENCY METER connector.

h. If the input frequency is known approximately, divide it by a harmonic number that gives a funda-

mental frequency in the range of the FREQUENCY dial. Set the FREQUENCY dial to this frequency.

i. Using a 0.01 second counter gate time and minimum display time, tune the COARSE VERNIER control until a vertical deflection is obtained on the oscillo-

scope. This deflection indicatee that some harmonic

of the transfer oscillator’s fundamental frequency is

sufficiently close to the input signal to produce a difference-frequency within the bandwidth of the oscilloscope. If more than one such beat frequency is obtainable, use the highest fundamental. Tune as close to zero beat as is convenient with the COARSE control.

Higher power

C. Set the HORIZ SWEEP INPUT switch on the rear

of the chassis to INT; set the line voltage selector to

the line voltage to be ueed.

d. Set the VIDEO RESPONSE-GAIN and HIGH FRE-

QUENCY controls to maximum clockwise position. 00161-2

j. Using a 0.01 second counter gate time and infinite dieplay time, tune the FINE VERNIER control to reduce the difference-frequency to as close to zero as the stability of the measured signal will allow. Press the counter RESET bution at the instant an exact zero beat is obtained. This allows the electronic counter

3-1

Page 32

Section III Figure 3-3

Model 540B

Figure 3-3. Controls. Indicators. and Connectors

Table 3-1. Function of Controls, Indicators, and Connectors (Sheet 1 of 2)

1. ON switch.

In ON position, applies power to instrument. In down position, removes power from instrument.

2. POWER indicator light. Glows when power is

applied to instrument.

3. FREQUENCY dial.

Adjusts and indicates the fundamental frequency generated by the internal oscillator, in MEGACYLES, within 1/2 percent.

4. COARSE VERNIER dial.

Adjusts the FRE-

QUENCY dial at reduced speed.

3-2

FINE VERNIER dial.

Adjusts the oscillator frequency electrically +125 cycles per megacycle from the frequency indicated by the FREQUENCY dial.

OSCILLATOR OUTPUT connector. the fundamental frequency for connection tothe Low Frequency or High Frequency Mixer, or Harmonic Generator.

FREQUENCY METER connector. Supplies an

7. output of the oscillator frequency for connection to an external electronic counter.

Supplies

00161-2

Page 33

Model 540B

Section III

Table 3-1

Table 3-1. Function of Controls, Indicators, and Connectors (Sheet 2 of 2)

8. HIGH FREQUENCY MIXER OR LOW FREQUENCY OSCILLATOR INPUT connectors. Accepts the fundamental frequency from the OSCILLATOR OUTPUT connector.

9. LOW FREQUENCY MIXER SIGNAL INPUT

connector. Accepts an input signal of 5 gc or less whose frequency is to be measured. This signal is mixed with harmonics of the oscillator frequency and the resultant signal is supplied at the MIXER OUTPUT connector.

10. HIGH FREQUENCY MIXER SIGNAL INPUT connector. Accepts an input signal between 1

and 12.4 gc whoee frequency is to be measured. This signal is mixed with harmonics of the oscillator frequency and the resultant signal is supplied at the MIXER OUTPUT connector.

11. HARMONIC GENERATOR OSCILLATOR INPUT connector. Accepts the signal from the OSCIL-

LATOR OUTPUT connector for generation of higher-order harmonics obtainable at the HARMONIC OUTPUT connector. When the transfer

oscillator is used for frequency measurement,

the necessary harmonics are generated in the

mixer, and this harmonic generator section is not used.

12. HARMONIC GENERATOR HARMONIC OUTPUT connector.

Provides high-order harmonics of

the signal applied to the HARMONIC GENERA-

TOR OSCILLATOR INPUT connector. These harmonics are for mixing with input signal frequencies above 12.4 gc using an external mixer. The output of the external mixer is then applied to the MIXER OUTPUT connector for display.

13. MIXER OUTPUT connector. Supplies the output signal from the Low or High Frequency Mixer for use by external equipment these mixer outputs are internally connected to the amplifier-oscilloscope section for display). This connector may also receive the output of an external mixer for display on the internal oscilloscope.

14. VIDEO OUTPUT BNC connector. Supplies the amplified output of the mixers for use by ex-

ternal equipment. Gain and bandwidth are controlled by the three VIDEO RESPONSE controls.

15. VIDEO RESPONSE-GAIN control. Controls amplification of the output from either internal mixer or from an external mixer connected to the MIXER OUTPUT jack, which drives the oscilloscope sod is available at the VIDEO

OUTPUT connector.

16. VIDEO RESPONSE-HIGH FREQ control. Ad- justs the frequency of the upper 3 db point of the amplified mixer output signal to the oscilloscope and the VIDEO OUTPUT connector from below 1 kc to above 2 mc.

NOTE: Although the signal available at the

VIDEO OUTPUT connector has a 2 mc bandwidth the oscilloscope responds only to frequencies up to approximately 200 kc.

17. VIDEO RESPONSE-LOW FREQ control. Adjusts the frequency of the lower 3 db point of

the mixer signal at the MIXER OUTPUT jack;

does not affect the bandwidth of the oscilloscope. At the extreme clockwise position, the 3 db point is switched to 100 cps. Moving off

the extreme CW position the 3 db point is

switched from 100

CPS to 10 kc, and then is

continuously adjustable to above 400 kc as the control is turned counterclockwise.

18. FOCUS control.

Adjusts the focus of the os-

cilloscope trace.

19. INTENSITY control. Adjusts the intensity of the oscilloscope trace.

20. HORIZ GAIN control. Adjusts speed to compress or widen the presentation.

21. 60 CYCLE PHASE control. Adjusts the phase of the internal, power line frequency sweep to

position the zero-beat frequency indication in the center of the screen.

22. HORIZ SWEEP INPUT toggle switch (on rear panel).

In INT. position, provides a line-

frequency sine-wave sweep for the oscillo-

scope, with phase adjustable by the front panel 60 CYCLE PHASE control. In EXT. position, allows a sweep signal to be provided from an external source connected to HORIZ SWEEP INPUT connector, and disables the front panel 60 CYCLE PHASE control.

23. HORIZ SWEEP INPUT BNC connector (on rear

panel). Accepts an external sweep signal. External sweeps must have an external phase control to position the zero-beat indication. This is used to synchronize the sweep when the carrier being measured is modulated at a rate different from the power line frequency.

24. FREQUENCY CONTROL BNC connector (on rear panel). Receives an externally-genetated, adjustable voltage or resistance to adjust the oscillator output frequency.

The maximum frequency variation from this control ie less than 0. 1%.

00161-1

3-3

Page 34

Section III Paragraph 3-5 (contd)

to measure the, transfer oscillator fundamental frequency at a precise moment, then hold the display.

On stable signals the oscilloscope trace will resemble figure 3-4. Absolute zero-beat will be obtained when the oscilloscope trace collapses into the horizontal

Since the frequency of most signals measured

line. is not stable enough to achieve this indication completely, various looped patterne are obtained as the measured frequency drifts about the exact point of zero-beat. Patterns such as illustrated in figure 3-5 are sufficiently close to zero-beat for most measurements, and are more practical to use than attempting to obtain a perfect zero-beat. Adjust the characteristic of the pattern by adjusting the VIDEO RESPONSEGAIN and HIGH FREQ. controls as desired.

When a very stable cw signal is being measured, the operator can initially adjust the transfer oscillator frequency until a beat-frequency presentation similar to A is obtained. As the operator refines the adjustment wfth the FINE VERNIER control, the oscilloscope pattern changes as shown in B and then collapses to almost-straight hortzontal lines, as shown in C when the true zero-beat is obtained. In practice, few signals are sufficiently stable to permit the simple pattern of C to be obtained. If the signal being measured has some residual frequency modulation the beat frequency patterns shown in figure 3-5 will be obtained.

Model 540B

When the frequency of the unknown signal vanes slightly (has some residual frequency modulation), the difference or beat frequency viewed on the oscilloscope also varies, and the exact zero-beat indication till be in the center of a band of difference frequencies all shown simultaneously on the oscilloscope screen. indications obtained with signals with varying amounts of residual frequent y modulation. Parts A and B show two typical beat-frequency responses from signals containing very minor amounts of frequency deviation; part C is the result obtained with a signal having a larger amount of frequency deviation. The exact zero-beat point is where the lines in the pattern become expanded horizontally. responses are obtained, notice first, that a low-beat frequency is approached, and then the exact zero-beat point begins to appear. This point moves about on the screen presentation and then disappears. Note that the zero-beat is traced twice per sweep, once in each direction, because the oscilloscope sweep is a sine wave. The 60 CYCLE PHASE control can be used to superimpose the two zero-beat traces in the center of the screen, if the residual frequency modu-

lation occurs at power line frequency. If the zerobeat traces cannot be stopped in one place, refer to paragraph 3-5 k for instructions for connecting an

external synchronizing signal.

This figure shows examples of zero-beat

When such

Figure 3-4. Typical Sequence of Oscilloscope

Patterns Obtained as Difference Frequency is Reduced to Zero, with a Stable CS Input Signal

k. The 60 CYCLE PHASE control can be adjusted

to position the zero beat point in the center of the

screen, provided the residual frequency modulation

occure at the power line frequency. If the zero beat

cannot be positioned with the 60 CYCLE PHASE con-

trol, frequency of the residual modulation on the car-

rier is different from the power line frequency. In thie case the zero-beat point is determined from the wideet zero-beat indication obtainable in the pattern that will sweep across the screen. If it ie necessary to etop the pattern in one place f or adequate measurement, apply to the rear HORIZ SWEEP INPUT connector a signal of the same frequency as the residual

modulation of the cw input. Switch the HORIZ SWEEP INPUT switch to the EXT. position. The oscilloscope horizontal sweep will now be synchronized with the residual modulation of the cw input signal, and the pattern will be stable. If the residual frequency-

3-4

Figure 3-5. Typical Oscilloscope Patterns

Obtained when CW Input Signal has some

Frequency Deviation

modulation is accompanied bv the amplitude modulation, the amplitude of the overall pattern on the oscilloscope will be altered without affecting readability or resolution. Amplitude modulation is indicated by a difference in amplitude of the pattern at the forward and backward traces on the oscilloscope. If the amplitude modulation occurs at the power line frequency, the phase control can be adjusted to superimpose the two traces and produce the familiar trapezoid associated with amplitude modulation. To measure the residual or the incidental frequency modulation, see paragraph 3-9.

1. Record the reading on the FREQUENCY dial, or

the number displayed on the Model 524 C/D Frequency

Counter (add the mixing frequency indicated on the Model 525B Frequency Converter, in accordance with

the frequency converter instruction manual). The

00161-1

Page 35

Paragraphs 3-6 to 3-8

Section III

counter reading is a more exact measurement of the fundamental frequency being generated by the transfer oscillator.

m. If the input frequency is known well enough that there can be no ambiguity between harmonics, divide it by the transfer oscillator fundamental frequency and round off the answer to the nearest even number. This is the number of the harmonic that beats with the input signal. If there is any ambiguity about the harmonic number, determine the exact harmonic in steps o through s.

n. Multiply the FREQUENCY dial reading or the counter indication by the harmonic number to obtain

the exact frequency of the input signal.

o. Slowly increase or decrease the fundamental frequency until the next adjacent fundamental is found whose harmonic produces a zero-beat indication. Watch the oscilloscope closely to assure that a weak indication of a zero-beat is not passed unnoticed, Record this fundamental frequency.

p. Using the appropriate nomograph in figures 3-6 and 3-7, locate the higher fundamental frequency recorded in steps 1 and o on the left column and the lower fundamental frequency recorded above on the center column.

q. Place a straight-edge across the two points and intersecting the right hand column. The point of in-

tersection on the right-hand column indicates the number of harmonic that beats with the input signal when the FREQUENCY dial is tuned to the higher of the two fundamental frequencies used.

r. If further assurance of accuracy is required,

such as with input signals containing large amounts of noise, or if the input frequency is above or below

those included in the nomography, use the first of the

following equations to determine the input frequency,

and the second or third equations to determine the

harmonic. Equation 1:

Equation 2:

Equation 3:

Note

To obtain accurate answers with the above equations, the fundamental frequencies must be read to 0.01% or better. In case the input signal being measured does not have this order of stability, it may be necessary to take the average of several fundamental fre quency readings for each beat-producing harmonic. read to 0.01% or better, the necessary division or multiplication can be carried out in longhand if highest accuracy is required, or

with a slide rule if this degree of accuracy is

satisfactory.

. To check the calculation performed in the step

With the fundamental frequencies

above, measure the next adjacent fundamental whose

harmonic produces a zero-beat indication. Recalculate, using the previously measured adjacent fundamental frequency.

Figures 3-6 and 3-7 are nomography of the

3-6. equations given in step r of paragraph 3-5. They are useful if the input frequency is between 400 and 5000

megacycles and can be determined from two adjacent transfer oscillator fundamental frequencies which produce zero-beat indications. In the nomograph, f the unknown frequency, f transfer oscillator frequencies whose harmonics produce zero-beat indications; f To use the nomograph, locate two adjacent fundamental

is the higher of two adjacent

is the lower frequency.

frequencies which zero-beat with the unknown input

signal. Find the higher of these two frequencies in left-hand column, the lower in the center column; place a straight-edge across these two points. The point where the straight-edge intersects the right-hand

column ie the number of the harmonic which beats

when the transfer oscillator is tuned to fl,

with f

Multiply f quency of the input signal (f

by the harmonic number to obtain the f re -

3-7. Transfer oscillator fundamental frequency can be read directly from the FREQUENCY dial with 1/2% accuracy. The dial reading can be used in the above equations for frequencies up to about 2000 megacycles, where low-order harmonics are used and the multiplied inaccuracy is reduced. To use the equations above 2000 mc the electronic counter must be used to read the fundamental frequency with sufficient accuracy to identify adjacent harmonics. However, if the harmonic which produces a beat frequency is already identified,

unknown frequencies above 2000 mega-

cycles can be measured to 1/2% accuracy by reading

the fundamental frequency directly from transfer os-

cillator FREQUENCY dial.

= frequency of unknown input signal

= two adjacent fundamental frequencies

whose harmonics produce zero beat

= harmonic number of f

N2 = harmonic number of f

00161-1

higher fundamental,

lower fundamental

3-8. The beat frequencies produced by the mixers in thie instrument are suitable only for frequency measurement as described in this manual.

These outputs are not suitable for amplitude measurements because the mixers are designed for best frequency coverage rather than calibrated amplitude responses.

A suitable external mixer must be used for applications where mixer output amplitude measurements are made.

3-5

Page 36

Section III

Figure 3-6

Model 540B

3-6

Figure 3-6. Nomograph for Determining a Harmonic Number of an

Unknown Frequency Between 400 MC and 2 GC from Two

Adjacent Frequencies Obtained with the 540B

Page 37

Model 540B

Section III

Figure 3-7

Figure 3-7. Nomograph for Determining a Harmonic Number of

Unknown Frequency Between 2 and 5 CC from Two

Adjacent Frequencies Obtained with the 540B

3-7

Page 38

Section III Paragraphs 3-9 to 3-13

3-9. MEASURING FM CARRIER FREQUENCY

AND LIMITS OF FREQUENCY DEVIATION.

3-10. To obtain readable zero-beat patterns when measuring the center-frequency and the limits of fre -

quency deviation in frequency-modulation carriers, the oscilloscope in the Model 540B must be swept by a signal of the same frequency that modulates the

carrier,

swept at the power line frequency. If the carrier being measured must be frequency-modulated at a rate different from the power-line frequency, this frequency

signal must also be applied to the HORIZ SWEEP INPUT connector on the rear of the transfer oscillator chassis and the HORIZ SWEEP INPUT switch must be set to the EXT. position. modulation which results in simple zero-beat presentations; non-sinusoidal modulation gives complex oscilloscope pictures.

3-11. When an external sweep input signal is used,

the 60 CYCLE PHASE control on the front panel is

inoperative, and it may be necessary to externally

adjust the phase of the sweep input signal to produce a stationary pattern such as shown in figure 3-8. The

oscilloscope presentation obtained when measuring

a frequency-modulated signal indicates much great er deviationtban when a cw signal with residual frequency

modulation was measured. The width of the zero-beat

point appears much smaller in relation to the full oscilloscope pattern, as shown in figure 3-8. Make measurements as follows:

a. Perform steps a through s of paragraph 3-4 to measure the carrier frequency. Refer to figure 3-8 for typical oscilloscope patterns.

b. Position the zero-beat pattern for the carrier frequency in the center of the oscilloscope screen.

c. With the FINE VERNIER control adjust the zerobeat indication slowly to one side of the oscilloscope screen, as shown in figure 3-8, parts B and C. This is either the lowest or highest frequency present in the carrier.

d. Compute this frequency as directed in paragraph

3-4, steps 1 through s.

e. Adjust the zero-beat to the opposite side of the oscilloscope, which corresponds to the limit of deviation on the opposite side of the carrier frequency.

f. Compute frequency as in step d.

3-12. MEASURING PULSED RF SIGNALS.

3-13. The carrier frequency of pulsed rf signals is measured by displaying a single pulse from the pulse

train as shown in figures 3-10 and 3-11, and adjust-

ing the transfer oscillator until a harmonic produces

a zero-beat indication with the carrier during the pulse. To observe a single pulse from the pulse train, an external oscilloscope with triggered sweep must be used instead of the transfer oscillator oscilloscope. Proceed as follows:

a. If the pulse width is greater than one micro-

second, connect the VIDEO OUTPUT connector of the

The Model 540B oscilloscope is internally

Use sine-wave frequency

Model 540B

When a frequency modulated signal is being meas-

ured, the beat frequency varies at tbe rate of the frequency modulation and it is not possible to reduce the zero-beat indication to a simple horizontal line

as in figure 3-11; instead, the zero-beat indication

aPPears in the center of a band of difference frequen cies similar to those of figure 3-5, but wfth the difference frequencies more tightly packed. The exact

zero-beat point is where the lines in the pattern become expanded horizontally. Parts A and D above show the zero-beat indic atione prope rly superimposed while the transfer oscillator is properly tuned to the carrier center frequency. Tbe amplitude of the difference frequencies on either side of center in D is decreased because the frequency deviation of the carrier is so great that display of the difference frequencies is limited by the bandwidth of the oscilloscope vertical amplifier. Parts B and C show the

presentation of the same signal as part A, as it

appears when the transfer oscillator is properly tuned first to one limit of frequency deviation and then the other, in making a measurement of maximum de-

viation above and below carrier frequency.

Figure 3-8.

when Input Signal is Frequency-Modulated

transfer oscillator to the vertical input jack of an external oscilloscope with triggered horizontal sweep. See figure 3-9 for a connection diagram.

b. If the pulse width is less than one microsecond,

connect the MIXER OUTPUT connector to an external

wideband amplifier, such as the@ Model 460 AR. Then

connect the output of the amplifier to the vertical in-

put jack of the oscilloscope. The external amplifier

is required because the mixer output contains frequencies beyond the passband of the transfer oscillator amplifier,

c. Connect the external sync jack of the oscilloscope to the sync output of the pulsed carrier modulator. If no suitable sync output is available a usable output

Typical Oscilloscope Patterns Obtained

3-8

00161-1

Page 39

Model 540B

Section III

Paragraph 3-13

Figure 3-9. Measuring Pulse-Modulated RF Signals

may be obtained by tapping off a portion of the pulsed carrier at a suitable point, and detecting the pulse envelope with a low-pass filter.

This envelope is

suitable for triggering the oscilloscope sweep.

d. Perform steps a through g of paragraph 3-5. For pulse carriers it is best to be able to adjust the input power to obtain at optimum oscilloscope pattern. If too much input power is applied in pulsed if measurements, the detected video pulse may obliterate ths desired beat frequency in the preeentaUon. Use only

enough power to obtain an easily read zero-beat.

e. If using the internal amplifier, turn all three VIDEO RESPONSE controls on the transfer oscillator fully clockwise for maximum gain and bandwidth.

00161-1

f. Adjust the input attenuator, initially, to provide almost 100 milliwatts of power. It may be necessary to reduce this input power to obtain an optimum zerobeat pattern.

g. Adjust the fundamental frequency of the transfer

oscillator to obtain the proper zero-beat pattern described below and illustrated in figure 3-10. The unknown frequency consists of pulses of an rf carrier; the mixer output consists of the difference frequency, lasting for the duration of each pulse. As the transfer oscillator is adjusted to bring a harmonic of the fundamental close to the frequency of the pulsed carrier, the difference frequency first appears as a sine wave within a pulse envelope, indicating that the difference frequency is great enough that several complete cycles

3-9

Page 40

Section III Paragraph 3-13

When the transfer oscillator frequency is adjusted to zero-beat wftha pulsed rf signal applied to the system, the first presentation usually recognized on the oscilloscope is similar to that of part A. In this case,

about five cycles of the difference frequency occur within each rf pulse envelope. For one-microsecond pulse this corresponds to a difference frequency of about 5 mc. As the transfer oscillator is fine-tuned

with the FINE VERNIER control, the number of difference-frequency cycles per pulse decreases as

shown in B, and finally becomes less than one cycle,

as illustrated in C. When the beat frequency is less

than one cycle a pattern like that in D is obtained.

The ideal zero-beat indication is when the pattern becomes agroupof horizontal traces.

Figure 3-10. Typical Patterns Obtained On

External Synchronized Oscilloscope, when

Measuring Pulse -Modulated RF Signals

fall within one pulse duration interval. As the zerobeat point is approached and the difference frequency

is reduced to the point where less than one cycle comes within each pulse interval, the waveform within the pulse envelope changes from sinusoidal (or nearly vertical) to horizontal.

The lines become nearly

horizontal when the beat frequency is essentially zero, where the difference frequency has such along period that it hardly changes within each pulse interval. If the signal under test were perfectly stable, the zerobeat indication would be one horizontal line within the pulse envelope. In practice, many horizontal lines appear.

The optimum zero-beat point occurs when

these horizontal lines have as little slope as possible.

3-10

Model 540B

This presentation of the difference frequency with a pulsed rf signal dees not require resolution of individual traces to identify the zero-beat. Zero-beat

is indicated when the first envelope of the differen-

tiated signal decays to a sharp point. Parts A, B,

and C illustrate difference frequencies of one, one-

tenth,

and one -hundredth cycle-per-pulsewidth,

respectively, approximately the counterparts of B,

C, and D in figure 3-10. Part C of this figure is

very close to the ideal zero-beat indications.

Figure 3-11. Typical Patterns Obtained on External

Synchronized Oscilloscope when the Pulse Pre-

sentations of Figure 3-10 are Differentiated

at the Oscilloscope Input

h. If the pulse repetition rate ie above 5 kc, horizontal traces at the optimum zero-beat point may be too crowded for optimum selection of the “best-horizontal” presentation. In this case insert a simple R-C differentiating circuit ahead of the vertical input

terminal of the oscilloscope as shown in figure 3-9.

The time constant of the R-C differentiating circuit should be on the order of one-tenth of the pulse width

of the pulsed carrier. The optimum zero-beat point is then indicated when the first envelope decays to the sharpest obtainable point as illustrated, in figure 3-11. If too short a time constant is used, decay to a sharp

point occurs in spite of a relatively high difference frequency, indicated by a lack of sensitivity of the

FINE VERNIER control over the narrowness of the

decay point. If too long a time constant is used, the decay point does not narrow even at zero-beat.

i. Carry out the frequency calculation and repeat measurements for harmonic number determination,

accuracy checks, etc.,

ase directed in steps 1 through

s of paragraph 3-5.

00161-1

Page 41

Model 540B

3-14. USE OF FREQUENCY CONTROL

CONNECTOR.

3-15. This rear panel connector permits electronically adjusting or frequency modulating the fundamen-

tal frequency generated by the transfer oscillator about 0.1% Variation of tbe oscillator frequency is accomplished by applying a steady or varying voltage or resistance, as desired, across the connector. The effect of this applied voltage or resistance is to alter the plate-to-ground capacity in the oscillator circuit to produce a slightly different frequency of oscillation. A constantly varying voltage or resistance will produce frequency modulation, while fixed steps of voltage or

resistance will produce incremental changes in the

fundamental frequency. Figures 3-12 and 3-13 sho typical frequency changes, in percent, produced by

various values of resistance and voltage connected

across the FREQUENCY CONTROL connector. Theee

are typical values which vary from instrument to instrument.

Paragraphs 3-14 to 3-17

Section III

Figure 3-13. Effect of Voltage Connected Across

FREQUENCY CONTROL Connector

c. Connect the unknown frequency in the range of

12.4 to 18 gc to the P-band waveguide input of the Model 932A. Use an input power greater than the minimum shown on the graph furnished with the Model

932A, but lese than 100 milliwatts.

NOTE

Figure 3-12. Effect of Resistance Connected

Across FREQUENCY CONTROL Connector

3-16. EXTENDING THE OPERATING RANGE

FROM 12.4 GC TO 18 GC.

3-17. The Model 540B Transfer Oscillator may be

used to measure frequencies from 12.4 to 18 gc by

Model 932A High Frequency Mixer.

This external mixer replaces the internal mixer which

is net suitable above 12.4 gc. To operate the tranefer oscillator in this range, follow the same operating procedures as given in the previous paragraphs, but connect the transfer oscillator as follows (see figure 3-14):

a. Connect the transfer oscillator OSCILLATOR OUTPUT connector to the OSCILLATOR INPUT connector on Model 932A through low-loss coaxial cable.

Greater watchfulness is required when measuring higher frequencies due to closer spacing and decreasing strength of the harmonics. In searching for zero-beat indications produced by adjacent harmonics, be careful not to skip an adjacent harmonic and unintentionally measure a non-adjacent one. As a precaution tune to a third adjacent harmonic producing a zero-beat frequency, ae shown in the example below. Uee the highest possible fundamental frequencies of the oscillator for greatest accuracy.

d. As an example of the fundamental frequencies and

adjacent harmonics that should be used to determine

the frequency of an approximate 18-gc carrier.

b. Connect the VIDEO OUT connector on the Model 932A to the MIXER OUTPUT connector on the transfer oscillator through low -loss coaxial cable.

00161-1

using the equations given in paragraph 3-5 r for computing the fundamental frequency and the number of the

harmonic causing a zero beat,

3-11

Page 42

Section III Paragraphs 3-18 to 3-22

Figure 3-14. Making Measurements at Frequencies between 12.4 and 18 gc

Model 540B

From this example it can be seen that an error in harmonic order will be easily detected, even if computations are made on a ten-inch slide rule.

3-18. MEASURING DETAILED CHARACTER-

ISTICS OF FM SIGNALS.

3-19. The transfer oscillator can be used in conjunction with other equipment for accurate measurement of the detailed characteristics of frequency-modulated rf carriers. The function of the transfer oscillator in this system is to reduce the frequency of the carrier to an intermediate frequency below 100 kilocycles

which retains the essential modulation characteristics.

These characteristics are detected by the 500B fol -

lowed by a low-pass filter, and measured by various test instruments - voltmeter, oscilloscope, distortion meter, wave analyzer.

3-20. The Hewlett -Packard 500B Frequency Meter

serves as a linear discriminator and converts the intermediate frequency carrier into a train of constant amplitude, constant-width output pulses -- one pulse for each rf input cycle (see figure 3-15). The average

current of these pulses is directly proportional to the intermediate frequency and is used to operate the Model 500B’s internal milliammeter, which is cali brated in kc. These pulses are supplied at the 500B’s

PULSE OUTPUT connector and are fed to the low-pass filter.

3-21. The low-pass filter blocks the 500B’s output pulse train and passes the average voltage of the pulses.

The voltage at the filter output varies at the

rate of the original modulating frequency and its a-c amplitude is directly proportional to the degree of frequency deviation. This voltage is then connected to additional test instruments (as shown in figure 3-15) to indicate frequency deviation, carrier drift, wave-

shape harmonic content and distortion.

3-22. To measure frequency deviation using an ac

vacuum tube voltmeter, adjust the dc voltage from the filter to be 1.414 volts when a 100-kc unmodulated

signal is applied to the 500B. This system is calibrated by loading the output of the low-pass filter with a 20,000 ohm potentiometer (equal to the 500B’s

PULSE OUTPUT jack characteristic impedance) and

adjusting the dc output of the filter to a predetermined

level for a known unmodulated input frequency.

3-12

00161-1

Page 43

Model 540B

Section III

Figure 3-15

Figure 3-15. System to Measure Frequency Modulation Characteristic

3-13

Page 44

Section III

Paragraphs 3-23 to 3-29

3-23. Abroad indication of carrier drift over nominal periods of time isobtained by observing the range of variation of the Model 500B’s meter readings. Drift measurements may be recorded by plugginga l-ma

recorder into the Model 500B’s RECORDER jack. A low -pass filter is not required for this application. because of the filtering already present at the jack.

3-24. Modulation frequencies and waveforms are ob-

served on an oscilloscope connected to the output of the low-pass filter.

Total distortion and harmonic

content can be measured directly on the Model 330B Distortion Analyzer and the Model 302A Harmonic Wave Analyzer. Theee measurements are relative and hence special calibrating procedures are not

required.

3-25. The cutoff frequency and the sharpness of the filter depend upon the degree of peak-to-peak carrier deviation and the highest modulating frequency since the sum of these two frequencies and the guard band between them (required by the finite alope of the cut-

off characteristic) must not exceed the 100 -kc pass band of the Model 500B. The three-section low-pass filter shown in figure 3-16 is sufficiently sharp to enable its use in a wide variety of applications. The

guard band of this filter is equal to twice the maxi-

mum modulating frequency. Thus the basic fm meas uring system equipped with this filter can handle

modulating frequencies up to 33 kc at very low deviations up to 50 kc at very low modulating frequencies. If greater peak deviation muet be measured, a filter

can be used or a system of frequency division employed.

The maximum peak deviation this three-section filter

will handle is given by the relationship:

where D

is the maximum peak deviation and F

mod

the maximum modulating frequency. For example,

the maximum peak deviation the basic system can

handle with a maximum modulating frequency of 15 kc is 27.5 kc:

3-26. GENERATING HARMONICS FOR

OTHER USES.

3-27. The oscillator and harmonic generator sections

of the transfer oscillator maybe ueed to produce very

accurate harmonics for calibration and other uses. To

provide these harmonics, connect the OSCILLATOR

Model 540B

Figure 3-16. Design Information for a Simple

Three-Section Low-Pass Filter

OUTPUT connector to the HARMONIC GENERATOR OSCILLATOR INPUT connector, Harmonics with the same accuracy as the fundamental frequency (which

3-28. MEASURING FREQUENCIES ABOVE

18 GC.

3-29. Figure 3-17 shows an arrangement for measuring frequencies above 18 gc. Harmonics in the 2-4 gc region are generated in the internal harmonic generator, amplified in the microwave amplifier, and applied to a tunable waveguide crystal mount which generates harmonics in the 18-40 gc region. The cliff erence frequency between one of these harmonics and the frequency being measured is detected in the Model 422 crystal detector and applied to the video amplifier of the 540B for presentation on the internal oscilloscope.

As the waveguide harmonic generator and the microwave amplifier both must be tuned, obtaining beat frequency indications is complicated but practical when the frequency of the unknown is known approximately.

3-14

00161-1

Page 45

SECTION IV

THEORY OF OPERATION

Paragraphs 4-1 to 4-3

Section IV

4-1. CIRCUIT DESCRIPTION.

How the Transfer Oscillator measures fre-

4-2. quency is best described by reference to the block diagram in figure 4-1. The 540B oscillator generatee a very stable fundamental frequency that is adjustable from 100 to 220 megacycles per second. Thts frequency is monitored by an electronic counter, and aleo supplied to either one of two crystal-diode mixers, or to a separate harmonic generator, depending upon the input frequency to be measured. The crystal mixers serve both as mixers and harmonic generators. When an input signal is also applied to the same mixer, mixing action occurs with all harmonice generated from the oscillator signal. If the difference between the in-

put signal frequency and some harmonic frequency is

less than the bandwidth of the following amplifier, a response will be seen on the oscilloscope. The fundamental frequency is then adjusted so that the harmonic frequency is exactly the same as the input frequency and the zero-beat is easily read on the os-

cilloscope display. The oscilloscope sweep is provided

by a sine wave of the power line frequency obtained

from the power transformer. As this sweep allows

synchronizing the display only when the frequency modulation of the input signal is also at the power line

frequency, provision is made to sweep the oscillo-

scope from an external signal introduced through a

connector on the rear panel, or by use of an external oscilloscope having a triggered sweep. A second amplifier supplies the same difference frequency to an output connector for display on the external oscillo-

scope. This output is used for obtaining large syn-

chronized displays of rf pulses.

4-3.

VARIABLE -FREQUENCY OSCILLATOR (100-

220 MC). The fundamental frequency of the transfer oscillator is generated by an extremely stable, pushpull Hartley oscillator and is brought out to the front panel at the OSCILLATOR OUTPUT connector. The signal is then normally coupled through a coaxial jumper to the OSCILLATOR INPUT connector of one of the mixers.

The housing for the oscillator, the

tuned circuit components and their mountings have all

Figure 4-1. Transfer Oscillator Block Diagram

00161-3 4-1

Page 46

Section IV Paragraphs 4-4 to 4-13

been made very rigid and the operating voltages applied to the circuit are well regulated. Although long-

term stability of this oscillator is not an important

factor, it is sufficient to afford 1/2% or better accu-

racy of the main tuning dial calibration.

4-4. Power is extracted from the oscillator by a fixed probe with its tip magnetically coupled to the oscillator plate fnductor. The probe provides a 50-ohm impedance at the front panel OSCILLATOR OUTPUT connector

(J7). Pickup for the signal obtained at the FREQUENCY

METER connector for monitoring purposes is not me-

chanically associated with the oscillator plate circuit although it is shown to be so on the schematic diagram. It is simply a resistor loop within the oscillator box. Coupling is adjusted so there is sufficient signal for operating the Model 524 Frequency Counter with Model 525B Plug-In Converter.

The oscillator circuit is tuned by a split-stator

4-5. capacitor (C27) and. a two-turn, center-tapped invar ribbon inductor (Ll). Trimmer capacitors C3 and C28 at each plate serve primarily to balance plate-toground capacity at the two sides of the plate tank to obtain maximum output power, and are also used to shift the calibration at the high-frequency end of the frequency dial by small amounts. Bias for both oscillator tubes, V1 and V2, is developed across the common cathode resistor. metrical, from each plate to the opposite grid. Heater and plate power are brought in through three separate rf filter circuits to prevent objectional conducted leakage of rf energy from the oscillator housing.

Signal feedback is sym-

Model 540B

and the video output jack on the rear of the housing.

The 1N416B ie a harmonic generator which supplies strong SHF harmonics from the oscillator output, which mix with the incoming signal in the 1N21B.

4-9.

VIDEO AMPLIFIER The video amplifier consists of the five resistance-coupled tube stages, V3, V4A and B, and V5A and B, two of which are cathode followers. imately 2 megacycles with the VIDEO RESPONSE controls set to maximum, and a gain of approximately 40 db is provided with the VIDEO GAIN control set to maximum. vide most of the amplification for both the VIDEO OUTPUT connector and the oscilloscope Vertical Amplifier. Tube V4B with its split load serves two pur-

poses: a cathode follower to drive the low-impedance,

low-frequency cutoff network at the input to video output tube V5, and a plate-loaded amplifier to feed the vertical oscilloscope amplifier, V6.

4-10. The high-frequency cutoff of the video amplifier is continuously adjustable by R4 in the grid circuit of

V3 from a maximum of 2 megacycles to a minimum of

1 kilocycle. The low-frequency cutoff point may be switched from 100 cps to 10 kc by S1 attached to R18. It is then continuously adjustable from 10 kilocycles to 400 kc by R18 (located in the grid circuit of V5A). Tube V5A makes up for the loss of gain in the low-

frequency response network while V5B provides a low

impedance termination at the VIDEO OUTPUT connector on the front panel.

The bandwidth of the amplifier is approx-

The first two stages, V3 and V4A, pro-

4-6. The FINE FREQUENCY VERNIER control is a

mechanical device which rotates a tilted aluminum disk

close to the plate tank inductor thereby affecting the plate circuit inductance very slightly. A second provision is made for very fine adjustment of the oscillator frequency by C46 and CR2 connected to the FREQUENCY CONTROL connector on the rear chassis.

Fine frequency adjustments can be made by either introducing a small, variable dc voltage or by varying the dc resistance betweenthis jack and ground, thereby changing the effective plate-to-ground capacity of the oscillator circuit.

The low frequency mixer assembly consists of

4-7. a transmission-line coupling between the OSCILLATOR

INPUT and SIGNAL INPUT connectors. The trans-

mission line is inside a housing which holds the mixer crystal and the difference-frequency output jack on the rear of the housing. The crystal mounting is a phenolic

sleeve that receives the crystal, pin-end first. The

crystal (a type 1N21B) is pressed into the housing to contact the junction bar which joins the OSCILLATOR

INPUT and SIGNAL INPUT connectors. The output connector when threaded onto the housing provides a slight pressure against the crystal to maintain a good contact with the junction bar.

4-8.

The high frequency mixer operates over the range of 1 to 12.4 gc. This mixer assembly consists of a transmission-line coupling between its corres-

ponding OSCILLATOR INPUT and SIGNAL INPUT con-

nectors.

which holds two crystals (one 1N21B and one 1N416B)

4-2

The transmission line is inside a housing

4-11. OSCILLOSCOPE VERTICAL AMPLIFIER. The

vertical amplifier consists of a single, resistance-

coupled pentode, V6, driving the upper vertical plate in the cathode-ray tube. This tube provides approximately 100 volts peak-to-peak and 40 decibels of gain over approximately a 200-kilocycle bandwidth without

compensation. 4-12. OSCILLOSCOPE HORIZONTAL AMPLIFIER

AND SWEEP CIRCUITS. The oscilloscope sweep circuit consists of a 6.3-volt line frequency voltage source, an adjustable phase-shifing network, R43 and

C 24, and a push-pull amplifier-phase inverter, V8. Resistance-coupled amplifiers V8A and V8B are cathode coupled in cascade to act both ss a phase-inverter and push-pull amplifier. both halves of V8 the plate load resistor for the B sec-

tion is made larger to compensate for the greater

degeneration in this stage. 4-13. POWER SUPPLY, A schematic diagram of the

power supply is shown in figure 5- . The power supply consists of an electronically regulated + 240 volt supply for operation of a majority of the circuits, an unregulated + 330 volt supply for amplifiers V6 and V8, an

unregulated -740 volt supply for the cathode-ray tube V7, and a special, regulated, multivibrator-driven heater supply for the oscillator tube filaments. The multivibrator supplies an oscillator filament voltage independent of line voltage variation. In newer models a slide switch on the rear panel selects the 1-mc voltage to be used. Power Transformer T1 can be wired

for operation on either 115 of 230 volts.

To obtain equal gain from

00161-3

Page 47

Section III Figure 3-17

Figure 3-17. Frequency Measurement above 18 gc with the 540B Oscillator

3-15/3-16

Page 48

Page 49

Model 540B Section V

SECTION V

MAINTENANCE

Paragraphs 5-1 to 5-16

5-1. INTRODUCTION.

5-2. The following paragraphs contain instructions for maintenance of the transfer oscillator. The components of this instrument are conservatively operated to provide maximum reliability with a minimum of repair. When trouble occurs, a systematic approach in

localizing the trouble to one section of the instrument will save maintenance time. In most cases, the trouble will be caused by a defective electron tube, and tube replacement will then restore operation. A list of the test equipment required for maintenance is given in table 5-1.

5-3. CABINET REMOVAL.

5-4.

To remove the transfer oscillator chassis from the cabinet, rest the instrument on a pad on its back to gain access to the bottom. Loosen the two large

slotted setscrews in the bottomed e of the panel bezel.

Withdraw these screws about 1/4 inch. The cabinet

is now free and can be lifted off the front panel and chassis. The rear cover may have to be removed to

gain access to some of the parta on the rear chassis.

WARNING

Be careful when making voltage measurements. Voltages as high as -740 volts dc are present in the chassis when power is applied.

5-5. PERIODIC CLEANING AND LUBRICATION.

5-6. No Lubrication is required. Once a year, remove the cabinet and carefully biow out accumulated

duet with a low-pressure air stream. Clean the in-

strument with a soft cloth.

5-7. TUBE REPLACEMENT.

5-8. In many cases, instrument malfunction can be corrected by replacing a defective tube. Before chang-

ing the setting of any internal adjustment, check the tubes. Adjustments made in an attempt to restore operation when the cause is a defective tube will often

complicate the repair problem. Check tubes by sub-

stitution rather than by using a tube tester, because

the results obtained with the tube tester may some-

times be misleading. Before removing a tubs, mark

it so that if the substitute tube does not improve op-

eration, the original tubs can be returned to the same

socket. Replace only those tubes proved to be weak

or defective. A circuit adjustment is provided for

those tube positions where variation in tubs character-

istics of the replacement tube may affect circuit per-

formance. Table 5-2 lists the tubes and test or ad-

justments which must be performed after replacement

of each particular tube.

5-9. TROUBLESHOOTING.

5-10. Before troubleshooting the transfer oscillator,

make sure that a trouble is not caused by poor external

connections, line power failure, or malfunctioning of the other equipment used with the transfer oscillator or the source of the signal under test.

troubleshooting by localizing the trouble to one of the

main sections of the instrument as directed in table

5-3. When the trouble hae been localized to a par-

ticular section, check the tubes in that section before

taking any other corrective action. If tube replace-

ment doee not eliminate the trouble, make sure that proper power is being provided by checking all power

supply outputs as directed in paragraph 5-13. Then

carry out detailed checks of the circuit components

other than tubes in the defective section, and continue

to other sections if necessary.

5-11. CALIBRATION.

5-12. PRELIMINARY INSTRUCTIONS. Use the pro-

cedure given in paragraphs 5-13 through 5-3 to test

and adjust each section of the transfer oscillator. Use

the entire procedure in the order given to carry out

a complete calibration check annually. Always check

the power supply section before testing or adjusting

and other section. The test equipment required for

calibration is listed in table 5-1. Equivalent instru-

ments may be substituted for those listed.

5-13. POWER SUPPLY TEST AND ADJUSTMENT.

5-14. Make voltage adjustments

+240 volt or Oscillator Filament Supply voltage is out-

side the limits given. Do not refine either setting if

the voltage is within limits. Always check the oscil-

lator filament supply after resetting the + 240 volt dc

supply.

5-15. TESTING THE +330 VOLT DC SUPPLY.

a. Connect the ground lead of the dc voltmeter to ground. With the dc probe, measure the + 330 volt dc supply at the point shown in figure 5-1.

b. Thie supply is unregulated and hae a nominal

voltage of+ 330 volts dc when the line input voltage is

115 volts ac. If the voltage is low, check V10, C43A, and C43B, or the current being drawn from the supply.

c. Check the total load current at the output from C43B, using the dc clip-on milliammeter. This total load current must be less than 100 ma.

5-16. TESTING THE + 240 VOLT DC SUPPLY. (See paragraph 1-11(4) for earlier model transfer oscillators using +225 volt dc supply. )

a. Connect the transfer oscillator to the Variac and set the Variac to supply 115 volts ac. Turn on and allow three-minute warmup.

b. Connect the ground lead of the dc voltmeter to ground.

Carry out

00161-3

5-1

Page 50

Section V Paragraph 5-17

Model 540B

Table 5-1. Test Equipment

Nomenclature

AC Vacuum Tube

Voltmeter ME-30

Vacuum Tube

Voltmeter

Model

Model 400D Measure low-frequency or

Model 410B Measure dc voltage and

ME -26

Application

low-level ac voltage

high-frequency ac voltage

Variable Auto- General Radio

Transformer Variac Model

Supply variable power

line voltage

W2, W5, or V-10 1 volt

Probe “T” Connector

Model 455A

In-line coaxial connection

with 410B voltmeter probe

50-ohm Coaxial Model AC-67A Matched termination for

Load

Model 455A

Electronic Model 524B/C/D Precise frequency

Counter

with Model 525B

measurement Plug-In Converter AN/USM-26

Square-Wave Model 211A Signal generator for am-

Generator

Oscilloscope Model 160B

plifier response test 0.5 volt, 0.02

Observe test waveforms

AN/USM-105A

Range

0. 1 mv to

Accuracy

± 2%

300 volts

1 to 1000 ydc

100 to 130 volts Voltmeter accu-

ac, 1.25 amp

rate within

100 to 200 mc

100 to 220 mc

1/10

or better

Approx 2 kc,

rise time

10 mc, trig-

gered sweep

Clip-On DC

Model 428A

Measure dc current

Milliammeter SHF Signal

Models 614A,

Measure mixer sensitivity

Generator 618B, and 620A

c. With the dc probe, measure the + 240 volt dc supply at the point shown in figure 5-1. This voltage must read + 240 ± 9 volts dc.

d. If the voltage is not + 240 ± 9 volts tic, adjust R73 in figure 5-1 to bring the voltage within these limits.

e. If the voltage cannot be adjusted and is too low, check V10 and Vll, and check the load current from

pins 3 and 6 of Vll with the clip-on dc milliammeter.

This current must be less than 90 ma.

f. If the voltage is too high, check V12. If voltage

fluctuates, check V13.

g. Check voltage regulation by adjusting the Variac to vary the line voltage from 103 to 127 volts ac while measuring the + 240 volt dc supply. The voltage must not vary more than ± 1 volt dc.

h. Measure the ac level across the +240 volt supply (at the same points to which the dc vtvm is connected) as the line voltage is varied from 102 to 127

volts ac rms with the Variac. The ac level must not

3 ma to 1 amp

± 3% ± 0.1 ma

0. 8 to 11 gc

exceed 5 millivolts. If ripple exceeds this level, test

Vll, V12, C43, and C41.

5-17. TESTING OSCILLATOR FILAMENT SUPPLY. The filaments of the tubes in the oscillator circuit are supplied by a multivibrator circuit which is operated from the regulated + 240 volts, thereby making the oscillator filament voltage independent of line voltage variations. However, the multivibrator eutput voltage is proportional to the value of the + 240 volts and must be checked if the setting of the +240 volts dc supply is changed. Since the multivibrator output voltage has a square waveform, care must be taken in the choice of a meter used to measure this voltage.

An rmscalibrated meter should be used for this measurement. A peak-responding meter cannot be used for this measurement. Meters which respond to the average but are calibrated for rms, such as the Model 400D/H/L recommended in table 5-1, are suitable when used with

the appropriate correction factor. The correction factor is necessary because this type of meter reads 1.11

times the true rms value of a square wave. Hence, if the actual square wave output voltage is 5.2 volts, this

5-2

00161-3

Page 51

Model 540B

Paragraphs 5-18 to 5-20

Section V

type of average - responding rms - calibrated meter would read 5.2 x 1.11 = 5.8 volts. Make the test as follows:

a. Connect a suitable ac vacuum tube voltmeter, as discussed above, between the lead at the top of the oscillator housing (shown in figure 5-1) and ground.

b. The true voltage at this point must be between

5.0 and 5.4 volts ac rms (5.6-6.0 as read ona Model 400D/H/L. If the voltage is within these limits do not change the setting. If this voltage is not within these limits, adjust R55 (figure 5-1) to obtain a true reading of 5.2 .(5. 8 as read on a Model 400D).

c. If the voltage cannot be adjusted and is too low,

check V9. Also check the load current drawn from

the secondary winding.

d. If step c does not correct the trouble, measure

the load current drawn from the secondary winding by

temporarily connecting a 0.1-ohm resistor in the cir-

cuit between terminal 4 of T2 and ground, and reading

the voltage drop across it. Load current must not ex-

ceed 0.6 ampere (which would correspond to a drop of 60 millivolts across a 0.1-ohm resistor or a voltage reading of 66.6 millivolts on the Model 400D/H/L).

Remove this resistor when measurement is completed.

5-18. TESTING THE -740 VOLT DC SUPPLY. TMe supply furnishes unregulated high voltage for the builtin oscilloscope, and should be checked if trace intensity becomes faint.

a. Connect the ground lead of the dc vtvm to ground.

With the dc. probe, measure the -740 volt dc supply at

the point shown in figure 5-1 (the non-grounded terminal of C40).

b. This supply has a nominal voltage of -740 volts dc when the line voltage is 115 volts ac. If the voltage is less than 690 volts, check the two semiconductor

rectifiers (CR6 and CR7) located on the bottom of the left-hand resistor board as viewed from the back of the instrument.

5-19. TESTING OSCILLATOR OUTPUT AND

DIAL CALIBRATION.

5-20. Following the replacement of tubes V1 or V2 in

the oscillator circuit, the nigh frequency end of the

main tuning dial may be slightly out of calibration and

the output voltage may be too low. Proceed as follows:

a. Turn on tbe transfer oscillator power and allow

20 minutes warmup time.

b. Using& coaxial “T” connector with a type N-to-

BNC adapter on each end, such as the

00161-3

Figure 5-1. Location of Measurement and Adjustment Points

5-3

Page 52

Section V Paragraphs 5-21 to 5-22

Model 540B

Table 5-2. Adjustments Required when Tubes are Replaced

Circuit

Reference Tube Type —

V1 V2 V3

V6 6CB6

V8 12AX7 Horizontal Amplifier Check horizontal trace centering, para 5-23

Vl0 Vll

V12 6CB6

6C4/6135 1/2 RF Oscillator 6C4/6135 1/2 RF Oscillator 6C4/6135 lst Video Amplifier

6U8

12AT7

2BP1 Cathode -Ray Tube

6350

5U4 6AS7

Function after Replacement of Tube

Adjust FREQUENCY dial calibration para 5-19 Adjust FREQUENCY dial calibration para 5-19

2nd & 3rd Video Amplifier

and Cathode Follower

4th Video Amplifier and

Cathode Follower

Oscilloscope Vertical

Amplifier

Heater Supply Adjust oscillator filament voltage, para 5-17

Multivibrator High Voltage Rectifier Series Voltage Adjust + 240 volt dc supply, paras 5-16, 5-17

Regulator Voltage Control Adjust + 240 volt dc supply, paras 5-16, 5-17

Check video response, para 5-21

Check vertical trace centering, para 5-23

Adjust horizontal and vertical position of

pattern, para 5-23

none

Test and/or Adjustment Required

para 5-21

V13

plug one of the top ends of the “T” into the OSCILLATOR OUTPUT connector. Terminate the other end of the top of the “T” with a proper 50-ohm termination,

such as the c. Unscrew the cap on the end of the ac probe of a the leg of the “T” connector. Measure the output volt-

age while turning the FREQUENCY dial through its full frequency range. The voltage must remain between

1.75 and 2.2 volts. If the voltage is below 2.0 volts at its highest point, replace V1 and/or V2.

d. Connect the front panel FREQUENCY METER connector to an electronic counter to measure the oscilloscope output frequency.

e. Set the FINE VERNIER dial to the mid-position

of its travel so that its white dot is up.

f. Compare the FREQUENCY dial indication to the

counter reading at each major dial calibration.

g. If the FREQUENCY dial reading is incorrect at

200 megacycles, readjust C3 and C28 (figure 5-1) to bring the frequency to 200 megacycles. Divide this adjustment equally between C3 and C28 to prevent dial error at low frequencies.

5651

Reference Tube Adjust + 240 volt dc supply, paras 5-16, 5-17

h. The oscillator output signal available at the FREQUENCY METER comector must have an amplitude of at least 0.2 volts when connected to a 50-ohm resistive termination through 50-ohm coaxial line. Use an os-

cilloscope or the Model 410B Vacuum Tube Voltmeter

for this measurement. If insufficient output is present,

check R51.

5-21. MEASURING VIDEO AM AMPLIFIER GAIN

AND RESPONSE.

5-22. To measure video amplifier response feed a fast pulse into the transfer oscillator and view the degradation of the waveshape on the oscilloscope. Pro-

ceed as follows:

a. Turn on the transfer oscillator and allow 5 min-

utes warmup; set VIDEO RESPONSE controls fully

clockwise.

b. Connect a square-wave generator to a teat oscil-

loscope and adjust the square-wave generator to provide 0,5 volts (peak) output at 2 kc as measured on the

test oscilloscope.

c. Connect the test oscilloscope to the transfer os-

cillator VIDEO OUTPUT connector.

5-4

00161-3

Page 53

Model 540B

Paragraphs 5-23 to 5-26

Section V

d. Reduce the equare-wave generator output 40 db, and connect it to the MIXER OUTPUT connector of the transfer oscillator.

e. The pattern viewed on the test oscilloscope

should have an equal or greater amplitude compared with step b, indicating that the transfer oscillator provides at least 40 db gain. If the amplifier does not provide efficient gain check V3, V4, V5, and V6.

Figure 5-2. Waveform Definitions

f. The overshoot on the waveform displayed on the test oscilloscope must be less than 25% (see figure 5-2). If greater overshoot is present, bend the leads

of capacitor C9 (between tube pins 1 and 2 of V4)

slightly to change that capacitor’s position until the

overshoot has been reduced to less than 25%.

g. The droop of the waveform top displayed on the test oscilloscope must be less than 10% (see figure 5-2). If it is not, check V3, V4, and C6 and adjust the value of C6 by padding if necessary.

5-23. CENTERING OSCILLOSCOPE TRACE.

5-24. To center the transfer oscillator oscilloscope

trace, proceed as follows:

a. Turn on the transfer oscillator and allow 5 min-

ute warmup.

b. Adjust oscilloscope controls to obtain a full-width

line on the screen.

c. Adust R32 (see figure 5-1) to center the hori-

zontal position of the line.

d. Adjust R34 (see figure 5-1) to center the ver-

tical position of the line.

5-25. MEASURING MIXER SENSITIVITY AND

FREQUENCY RESPONSE.

5-26. Mixer sensitivity is defined as the minimum input signal power which will give an output amplitude from the mixer 6 db above the noise level. To measure sensitivity and frequency response, proceed

as follows:

a. Turn all VIDEO RESPONSE controls fully clock-

wise.

b. Connect the jumper cable between the OSCILLATOR OUTPUT connector and the OSCILLATOR INPUT connector of the mixer to be checked.

c. Connect the ac vtvm to the VIDEO OUTPUT connector, This measurement reads noise.

d. Connect a signal generator of the appropriate

frequency to the SIGNAL INPUT connector of the mixer

being checked. Check the Low Frequency Mixer at 1 and 4 gc, the High Frequency Mixer at 4, 8, and 11 gc.

h. The rise time (10%-90%) of the pattern displayed

on the test oscilloscope must be 0.22

not, check V3 and V4.

e. Adjust the signal generator output until the voltage reading on the ac vtvm is exactly twice the value noted in step c. The input power being supplied by

Table 5-3. Trouble Localization

Indication of Trouble

Items to Check

Instrument inoperative; POWER light does not glow Check power connections and fuse F1

Check continuity of T1 primary windings Instrument inoperative; POWER light glows No horizontal trace appears on oscilloscope

Check power supply output voltages and VI Check that HORIZ SWEEP INPUT switch is

in INT position

Check V8

Horizontal line appears on oscilloscope but no

Check tubes V3, V4, and V6

vertical trace

Cannot obtain beat frequency

Check oscillator output

Check mixer by using other mixer or

replacing crystal

00161-3

5-5

Page 54

Section V Paragraphs 5-27 to 5-31

the signal generator at this point is the sensitivity of the mixer at that frequency.

f. To measure the frequency response of a mixer, measure sensitivity while adjusting the input signal frequency to cover the entire range of the mixer.

Typical sensitivity of the mixers is shown in figure

3-2. The sensitivity of individual mixers may vary at certain frequencies; variations up to ± 10 db are acceptable.

Mixers with poorer response than this may be replaced. However, the crystals furnished with the instrument have been selected for best overall performance (an absence of points of poor response throughout the band). If a crystal is replaced to se-

cure higher gain at a particular frequency, keep the

original crystal for general use.

5-27. REPLACING PARTS IN THE LOW

FREQUENCY MIXER.

5-28. REPLACING THE 1N21B CRYSTAL. The low frequency mixer contains one 1N21B crystal diode

which has been selected to give most uniform har-

monic generation and frequency mixing, and freedom from dead spots, from 200 mc to 4 gc. The crystal is easily changed as follows (see figure 5-3):

a. Unscrew the cylindrical portion of the mixer

from the rectangular body to gain access to the crystal.

b. Pull the crystal from the body.

c. Insert replacement crystal 2N21B into the body.

d. Replace the cylindrical cover.

5-29. A replacement crystal may not give exactly the

same sensitivity or noise level. If, after the crystal

is replaced, the noise level is too high or the sensi-

tivity is too low, try another replacement crystal. In

Model 540B

a given crystal sensitivity will vary with the input frequencies; in addition, the sensitivity curve of one crystal will differ from that of another. The selection of a

crystal can thus be for best overall sensitivity across the full frequency band or for maximum sensitivity in a chosen narrow band of frequencies. In the latter

case, there may be frequencies outside the chosen bands where sensitivity drops below normal which are

considered unimportant. Once this crystal is replaced, the original specified sensitivity across the frequency

band can no longer be guaranteed unless the transfer oscillator is returned to the factory for recalibration.

5-30. REPLACING PARTS IN THE HIGH

FREQUENCY MIXER.

5-31. REPLACING THE 1N21B CRYSTAL. The high frequency mixer contains two crystal diodes, one

1N21B and one 1N416B. The two diodes have different

effects on operation and only the 1N21B is field replaceable.

The description of performance given for the 1N21B in the low-frequency mixer applies also to the 1N21B in the high - frequency mixer.

Once the crystal is replaced, the original specified sensitivity across the frequency band can no longer be guaranteed unless the transfer oscillator is returned to the factory for recalibration.

To replace the 1N21B crystal in

the high-frequency mixer, proceed as follows:

a. Refer to figure 5-4; remove the connector cap

from tine filter assembly to gain access to crystal.

b. Being careful to prevent discharge of static electricity through the crystal diode, remove the crystal from the filter assembly. Such a discharge is only remotely possible and is easily prevented by having one’s body grounded at the moment the crystal is touched.

c. Insert replacement crystal 1N21B into the filter assembly and install connector cap on filter assembly.

Figure 5-3. LOW Frequency Harmonic Mixer

5-6

Figure 5-4. High Frequency Harmonic Mixer

00161-3

Page 55

Model 540B

Paragraphs 5-34 to 5-36

Section V

5-32. REPLACING THE lN416B CRYSTAL. The

1N416B crystal may be replaced in the field for emergency operation, but in most a fine adjustment in penetratio bly to regain original sensitivity across the full frequency band. differs from the effect of the 1N21B in that it has greater effect upon the overall sensitivity and on noise level, and there is less effect upon sensitivity over

narrow frequency bands (holes).

1N416B crystal, proceed as follows:

a. Refer to figure 5-4; remove the filter assembly (with connector cap remaining installed) from the mixer body to gain access to the crystal.

b. Being careful to prevent discharge of static electricity through the crystal diode, remove the crystal from the mixer body by a straight pull with a longnose pliers. Such static discharge is only remotely possible and is easily prevented by having one’s body grounded at the moment the crystal is touched.

c. A replacement 1N416B crystal has a cap on one end of its body. Remove this cap, noting the capped end.

d. With a pair of long-nosed pliers, insert replace-

ment crystal into the mixer body, capped end last.

e. Install filter assembly on mixer body. 5-33. REPLACING THE FILTER ASSEMBLY. The

filter assembly on the high-frequency mixer can be replaced as a unit without need for subsequent adjustment. Do not attempt to repair any internal part of the filter assembly. The filter assembly contains an inductor which consists of a short piece of 0.001 inch diameter copper wire. To check for continuity, use a 20,000-ohm/volt multimeter on a high range. Excessive current will quickly burn out this wire. To replace the filter assembly, proceed as follows:

The effect of replacing the 1N416B

the probe assem-

To replace the

a. Loosen both the knurled nuts that secure the

probe assembly to the front panel. Remove outer nut.

b. Remove both BNC cables from rear of mixer

assembly.

c. Remove mounting screws that secure assembly to the front panel, and remove assembly from transfer oscillator.

d. Loosen the two #8 allen setscrews on the collar and remove the probe assembly from the mixer body, unscrewing inner knurled nut to allow probe assembly to be removed through panel hole.

e. Install the replacement probe assembly with

care. Do not force it down into the mixer body. After

the probe has touched bottom, lift is slightly less than

1/128 inch (approximately .005 inch), and tighten the

allen setscrews on the collar.

f. Thread inner knurled nut well down on probe assembly so it will not strike panel when being installed in transfer oscillator.

5-35. HARMONIC GENERATOR ASSEMBLY.

5-36. The 1N21B crystal diode used in the harmonic

generator is selected at the factory to give good har-

monic generation above 1 gc from a 200-mc fundamental. The crystal can be replaced in the field; proceed as follows:

a. Refer to figure 5-5; remove generator body from

the connector.

b. Remove crystal 1N21B from the connector.

c. Insert replacement crystal 2/21B into the connector.

a. Refer to figure 5-4; remove the connector cap

from the filter assembly.

b. Remove the crystal from the filter assembly.

c. Remove the filter assembly from the mixer body.

d. Install the replacement filter assembly on the

mixer body.

e. Install the crystal in the filter assembly.

f. Install the connector cap on the filter assembly

and connect cable.

5-34, REPLACING AND ADJUSTING THE PROBE

ASSEMBLY. The probe assembly may be replaced in the field for emergency operation, but requires fine adjustment of the probe penetration to regain original

sensitivity across the full frequency band. Do not at-

tempt to replace any of the internal parts of the probe

assembly. To replace the probe assembly, proceed

as follows: 00161-3

d. Restore generator body to connector.

Figure 5-5. Harmonic Generator

5-7

Page 56

Section V

Figure 5-6

Model 540B

5-8

Figure 5-6. Oscillator Assembly

00161-3

Page 57

Model 540B

Section V

Figure 5-7

00161-3

Figure 5-7. Chassis Board, Parts Location

5-9

Page 58

Section V

Figure 5-8

Model 540B

5-10

Figure 5-8. Resistor Board, Parts Location

00161-3

Page 59

Model 540B

Section V

Figure 5-9

00161-3

Figure 5-9. Voltage and Resistance Diagram

5-11

Page 60

Section V Figure 5-10

Model 540B

5-12

Figure 5-10. Power Supply

00161-1

Page 61

Figure 5-11. OscilIator Schematic

(Located in back of Manual)

5-13/5-14

Page 62

Page 63

SECTION V.1

PREVENTIVE MAINTENANCE INSTRUCTIONS

5.1-1. SCOPE OF MAINTENANCE

The maintenance duties assigned to the operator and organizational

repairman of the equipment are listed below together with a reference to the

paragraphs covering the specific maintenance functions.

Daily preventive maintenance checks and services (para 5.1-4).

Weekly preventive maintenance checks and services (para 5.1-5).

Monthly preventive maintenance checks and services (para 5.1-6).

Quarterly preventive maintenance checks and services (para 5.1-7).

Cleaning (para 5.1-8).

Touchup painting (para 5.1-9).

5.1-2.

PREVENTIVE MAINTENANCE

Preventive maintenance is the systematic care, servicing, and inspection

of equipment to prevent the occurrence of trouble, to reduce downtime, and

to assure that the equipment is severiceable.

a. Systematic Care. The procedures given in paragraphs 5.1-4 through

5.1-8 cover routine systematic care and cleaning essential to proper upkeep and operation of the equipment.

b. Preventive Maintenance Checks and Services. The preventive maintenance

checks and services charts (para 5.1-4 through 5.1-7) outline functions to

be performed at specific intervals.

These checks and services are to

maintain Army electronic equipment in a combat-serviceable condition; that

is, in good general (physical) condition and in good operating condition. To assist operators in maintaining combat serviceability, the charts indicate what to check, how to check, and what the normal conditions are; the

References column lists the illustrations, paragraphs, or manuals that

contain detailed repair or replacement procedures.

If the defect cannot be

remedied by performing the corrective actions listed, higher echelon maintenance or repair is required.

Records and reports of these checks and services must be made in accordance with the requirements set forth in TM 38-750.

5.1

PREVENTIVE MAINTENANCE CHECKS AND SERVICES PERIODS

Preventive maintenance checks and services of the equipment are

required daily, weekly, monthly, and quarterly.

5.1-1

Page 64

Page 65

Para 5.1-8.

5.1-3

Page 66

5.1-4

Para 5.1-9.

Page 67

5.1-5

Page 68

5.1-6

TM 38-750.

Page 69

5.1-8. CLEANING

Inspect the exterior of the equipment.

The exterior surfaces should be

clean, and free of dust, dirt, grease, and fungus.

a. Remove dust and loose dirt with a clean soft cloth.

Warning

Provide adequate ventilation.

: Cleaning compound is flammable and its fumes are toxic.

Do not use near a flame.

b. Remove grease, fungus, and ground-in dirt from the case; use a

cloth dampened (not wet) with Cleaning Compound (Federal stock No. 7930-395-9542).

c. Remove dust or dirt from plugs and jacks with a brush.

Caution:

Do not press on the face (glass) of the cathode ray tube when

cleaning; the cathode ray tube may be damaged.

d. Clean the front panel and control knobs; use a soft clean cloth. If dirt is difficult to remove, dampen the cloth with water; use mild soap if necessary.

5.1-9. TOUCHUP PAINTING INSTRUCTIONS.

Remove rust and corrosion from metal surfaces by lightly sanding them

with fine sandpaper. Brush two thin coats of paint on the bare metal to protect it from further corrosion.

Refer to the applicable cleaning and

refinishing practices specified in TM 9-213.

5.1-7

Page 70

Page 71

Model 540B

TM 11-6625-493-15

CODE LIST OF MANUFACTURERS (Sheets 1 of 2)

i-1

Page 72

TM 11-6625-493-15

CODE LIST OF MANUFACTURERS (Sheet 2 of 2

Model 540B

i-2

Page 73

APPENDIX I

REFERENCES

TM 11-6625-493-15

DA Pam 310-4

SB 11-573

TB SIG 364

TM 9-213

TM 11-5134-15

TM 11-5527

TM 11-6625-274-12

TM 11-6625-316-12

TM 11-6625-320-12

TM 33-750

Index of Technical Manuals, Technical Bulletins, Supply Manuals (types

7, 8, and 9), Supply Bulletins, Lubrication Orders, and Modification Orders.

Painting and Preservation Supplies Available for Field Use for Elec-

tronics Command Equipment.

Field Instructions for Painting and Preserving Electronics Command

Equipment.

Painting Instructions for Field Use.

Organizational, DS, GS and Depot Maintenance Manual: Signal Generators

SG-299/U, SG-299A/U, SG-299B/U, and SG-299C/U.

Multimeters TS-352 U, TS-352A/U, and TS-352B/U.

Operator’s and Organizational Maintenance Manual: Test Sets, Electron

Tube TV-7 U, TV-7A/U, TV-7B/U, and TV-7D/U

Operator and Organizational Maintenance Manual; Test Sets, Electron

Tube TV-2/U, TV-2A/U, TV-2B/U, and TV-2C/U.

Organizational Maintenance Manual: Voltmeter, Meter ME-30A/U and

Voltmeters, Electronic ME-30B/U, ME-30C/U, and ME-30E/U.

Army Equipment Record Procedures.

Page 74

Page 75

APPENDIX II

BASIC ISSUE ITEMS LIST

Section I. INTRODUCTION

TM 11-6625-493-15

1. General

This appendix lists items supplied for initial operation and for running spares. The list includes tools, parts, and material issued as part of the major end item. The list includes all items authorized for basic operator maintenance of the equipment. End items of equipment are issued on the basis of allowances prescribed in equipment authorization tables and other documents that are a basis for requisitioning.

2. Columns

Columns are as follows:

a. Federal Stock Number. This column lists

the 1l-digit Federal stock number.

b. Designation by Model. Not used.

c. Description. Nomenclature or the stand-

ard item name and brief identifying data for each item are listed in this column. When

requisitioning, enter the nomenclature and description.

d. Unit of issue. The unit of issue is each unless otherwise indicated and is the supply term by which the individual item is counted for procurement, storage, requisitioning, allow-

ances and issue purposes.

e. Expendability. Nonexpendable items are indicated by NX. Expendable items are not annotated.

f. Quantity Authorized. Under “Items Comprising an Operable Equipment,” the column lists the quantity of items supplied for the initial operation of the equipment. Under “Running Spare Items” the quantities listed are those issued initially with the equipment as spare parts. The quantities are authorized to be kept on hand by the operator for maintenance of the equipment.

g. Illustration. The “Item No.” column lists the reference symbols used for identification of the items in the illustration or text of the manual.

i-5

Page 76

SECTION II.

i-6

Page 77

i-7

Page 78

Page 79

APPENDIX Ill

MAINTENANCE ALLOCATION

Section I. INTRODUCTION

TM 11-6625-493-15

1. General

a. This appendix assigns maintenance functions to be performed on components, assemblies, and subassemblies by the lowest appropriate maintenance category.

b. Columns in the maintenance allocation chart are as follows:

(1) Part or component. This column

shows only the nomenclature or standard item name. Additional descriptive data are included only where clarifi-

cation is necessary to identify the

component. Components, assemblies, and subassemblies are listed in topdown order. That is, the assemblies which are part of a component are listed immediately below that component, and subassemblies which are part of an assembly are listed immediately below that assembly. Each generation breakdown (components,

assemblies,

listed in disassembly order or alphabetical order.

(2) Maintenance function. This column

indicates the various maintenance functions allocated to the categories.

Service. To clean, to preserve, and

(a)

to replenish lubricants.

Adjust. To regulate periodically to

(b)

prevent malfunction.

Inspect. To verify serviceability

(c)

and detect incipient electrical or

mechanical failure by scrutiny.

Test. To verify serviceability and

(d)

to detect incipient electrical or me-

chanical failure by use of special equipment such as gages, meters, etc.

Replace. To substitute service-

(e)

able components, assemblies, or

or subassemblies) are

subassemblies, for unserviceable components, assemblies, or subassemblies.

Repair.

(f)

serviceable condition through correction of a specific failure of unserviceable condition. This function includes but is not limited to welding, grinding, riveting, straightening, and replacement of parts other than the trial and error replacement of running spare type items such as fuses, lamps, or electron tubes.

Align. To adjust two or more com-

(g)

ponents of an electrical system so that their functions are properly synchronized.

(h)

Calibrate. To determine, check, or

rectify the graduation of an instrument, weapon, or weapons system, or components of a weapons system.

(i)

Overhaul. To restore an item to

completely serviceable condition an

prescribed by serviceability standards. This is accomplished through employment of the technique of “Inspect and Repair Omy as Neces-

sary” (IROAN). Maximum utili-

zation equipment is combined with minimum disassembly of the item during the overhaul process.

(j) Rebuild. To restore an item to a

standard as near as possible to original or new condition in appear-

ance, performance, and life expectancy. This is accomplished through the maintenance technique of complete disassembly of the item, inspection of all parts or repair or replacement unserviceable elements

To restore an item to

of diagnostic

and test

components,

of worn or using origi-

i-9

Page 80

TM 11-6625-493-15

nal manufacturing tolerances and/ or specifications and subsequent reassembly of the item.

(3)

Operator, organizational, direct support, general support, and depot. The

symbol X indicates the categories re-

sponsible for performing that particu-

lar maintenance operation, but does

not necessarily indicate that repair parts will be stocked at that level. Categories higher than those marked by X are authorized to perform the indicated operation.

Tools required. This column indicates

(4)

codes assigned to each individual tool equipment, test equipment, and maintenance equipment referenced. The

grouping of codes in this column of the maintenance allocation chart indicates the tool, test, and maintenance equipment required to perform the

maintenance function.

Remarks. Entries in this column will

(5)

be utilized when necessary to clarify

any of the data cited in the preceding column.

c. Columns in the allocation of tools for

maintenance functions are as follows:

Tools required for maintenance func-

(1)

tions. This column lists tools, test, and maintenance equipment required to perform the maintenance functions.

(2)

Operator, organizational, direct support, general support, and depot. The

dagger (†) symbol indicates the categories normally allocated the facility.

Tool code. This column lists the tool

(9)

code assigned.

2. Maintenance by Using Organizations

When this equipment is used by signal services organizations organic to theater headquarters or communication zones to provide theater communications, those maintenance functions allocated up to and including general support are authorized to the organization operating this equipment.

i-10

Page 81

SECTION II.

i-11

Page 82

SECTION III.

i-12

Page 83

Section V Figure 5-11

Page 84

By Order of the Secretary of the Army:

Official:

J. C. LAMBERT,

Major General, United States Army,

The Adjutant General.

Distribution:

Active Amy:

TM 11-6625-493-15

HAROLD K. JOHNSON,

General,

United States Army,

Chief of Staff.

USASA (2) CNGB (1) CofT (1) CofEngrs (1) TSG (1)

Cofspts (1) CC-E (2) USAARMBD (2) USAARTYBD (2)

USCONARC (2) USAMC (2)

USAMICOM (2) USAECOM (2) USASCC (2) ARADCOM (2) ARADCOM Rgn (2) OS Maj Cored (2) OS Base Cored (2) USASMC (3)

USASA 1st Fld Sta (1)

USACDCDA :

Ft Huachuca (1)

Ft Monmounth (1) USAEMSA (15) Lexington A Dep (6) Sacramento A Dep (6)

NG: None.

Tobyhanna A Dep (6) Letterkenny A Dep (5) Ft Worth A Dep (5) Sharpe A Dep (3) Navajo A Dep (6) Charleston A Dep (1) Savanna A Dep (5) Svc Colleges (1) 11th Air Assault Div (3) GENDEP (OS) (1) Sig Sec GENDEP (OS) (4) Sig Dep (OS) (6) Chicago Proc Dist (1) Ft Huachuca (1) WSMR (1) USAELRDL (6)

USAERDL (2) CRREL (2) Oakland A Tml (5) Units org under fol TOE:

(2 copies each)

11-15E

11-587

11-692

11-697

USAR: None.

For explanation of abbreviation used, see AR 320-50.

Page 85

Page 86

Page 87

Page 88

Page 89

PIN: 020795-000

HP 540b schematic

Specifications and Main Features

Frequently Asked Questions

User Manual

Figure 1-1

SECTION I

Table 1-1

Section II

Figure 3-1

Section III

Figure 3-6

Figure 3-7

Figure 3-15

SECTION IV

SECTION V

para 5-21

Figure 5-6

Figure 5-7

Figure 5-8

Figure 5-9

APPENDIX I

APPENDIX II